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Tên tác phẩm: Người Mặt Nạ Đen ở nước An-giép (Черная маска из
Аль-Джебры)
Tác giả: Владимир Лёвшин и Эм. Александрова
Dịch giả: Phan Tất Đắc
Nhà Xuất Bản Kim đồng 1978
Scan: ICT
Đánh máy: tongdh, welcome1985, kajerin, FlameriusTino
Soát lỗi: 4DHN, trungkien45
Làm ebook: 4DHN


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MỤC LỤC
VÀI LỜI GIỚI THIỆU................................................................................. 5
ĐOẠN MỞ ĐẦU ........................................................................................... 6
TRỞ LẠI NƯỚC TÍ HON ....................................................................... 6
TRUY TÌM .............................................................................................. 17
NHỮNG BỨC THƯ .................................................................................... 20
CHẶNG ĐƯỜNG HÀNH QUÂN.......................................................... 20
NHỮNG NGƯỜI PHÀM ĂN ................................................................ 22
CON ĐƯỜNG MỘT RAY LƠ LỬNG TRÊN KHÔNG ..................... 27
MỞ TRƯỜNG HỌC Ở QUẢNG TRƯỜNG SỐ ................................. 35
CÁC QUY TẮC VẬN HÀNH ................................................................ 37
VƯỜN HOA TRUNG TÂM “KHOA HỌC VÀ NGHỈ NGƠI” ......... 41
VỤ ẨU ĐẢ GIỮA HAI SỐ KHÔNG .................................................... 46
CHẬT CHỘI THẬT, NHƯNG KHÔNG PHIỀN LỤY AI................. 47
NGƯỜI QUAI BÖA ................................................................................ 53
SỐ KHÔNG - ANH LÍNH BIÊN PHÕNG ........................................... 58
HỘI GIẢ TRANG ................................................................................... 60

VÕNG DANH DỰ ................................................................................... 65
NHỮNG CHIẾC MŨ NỒI SẶC SỠ...................................................... 70
TƯỜNG THUẬT TỪ SÂN VẬN ĐỘNG .............................................. 72
NHỮNG NGƯỜI THỢ LÀM BÁNH KIÊM NGHỆ SĨ TUNG HỨNG
................................................................................................................... 78
THƯ CỦA SỐ KHÔNG GỬI RIÊNG CHO XÊ-VA .......................... 86
“ÖM BA LA” ........................................................................................... 88
TẬP TẦM VÔNG, TAY NÀO KHÔNG, TAY NÀO CÓ ................... 95
GẶP LẠI NGƯỜI QUEN BIẾT CŨ ................................................... 100
CÁNH CỬA HÀNG RÀO CUỐI CÙNG ........................................... 107
ĐƠN GIẢN VÀ KHÓ TIN ................................................................... 110
NHỮNG PHÁT HIỆN MỚI CỦA SỐ KHÔNG ................................ 118
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MỘT THỰC TẾ MẦU NHIỆM .......................................................... 122
PHÕNG CÂN ĐO ................................................................................. 124
AN-GIÉP! .............................................................................................. 132
VỌT LÊN RỒI LẠI TỤT XUỐNG! ................................................... 137
ĐU QUAY ẢO ....................................................................................... 142
AN-MU-CA-BA-LA!............................................................................. 149
GẦN ĐẾN ĐÍCH RỒI .......................................................................... 156
PÔN-SÍCH BỊ MẮC CÂU ................................................................... 163
KHÁM PHÁ ĐƯỢC BÍ MẬT RỒI! .................................................... 167
VÀO SÂU TRONG ĐẤT NƯỚC AN-GIÉP ...................................... 174
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VÀI LỜI GIỚI THIỆU

Năm 1976 Nhà xuất bản Kim Đồng đã cho in cuốn “Ba ngày ở nước Tí
hon” của nhà văn kiêm nhà toán học Liên Xô V. Li-ốp-sin. Những ai đã đọc
cuốn sách đó đều cùng với ba bạn học sinh Ta-nhi-a, Ô-lếch và Xê-va tham
gia một chuyến du lịch thú vị vào nước Tí hon, xứ sở của các con số. Qua

những chuyện mà các bạn nhỏ đó đã gặp trong ba ngày du lịch tại thủ đô A-
ra-ben-la của Quốc gia số học, trong rạp xiếc của người Tí hon, trên sân
băng, tại phố Gương… chúng ta đã được biết nhiều điều kỳ thú và bổ ích về
các con số, về lịch sử cũng như các tính chất cơ bản của chúng.
Lần này, chúng tôi xin hân hạnh giới thiệu tiếp với các bạn đọc cuốn
“Người Mặt Nạ Đen ở nước An-giép”, là cuốn truyện thứ hai tiếp theo cuốn
“Ba ngày ở nước tí hon”, do V. Li-ốp-sin viết chung với nhà văn E. A-lec-
xan-đrô-va. Các tác giả sẽ đưa các bạn đọc đi thêm một chuyến du lịch nữa
vào xứ sở các con số, đến nước An-giép tức là nước Đại số, láng giềng của
nước Số học. Các bạn sẽ gặp lại các nhân vật quen thuộc, cùng với họ giải
bùa cho Người Mặt Nạ Đen. Chắc chắn là các bạn đọc cũng sẽ rất hài lòng
như các nhân vật trong truyện, bởi vì trong việc giải bùa cho Người Mặt Nạ
Đen có đòi hỏi các bạn phải lao động tí chút, song các bạn sẽ được gặp
nhiều chuyện lí thú và nhất là sẽ học được cách lập và giải phương trình bậc
nhất.
Mời các bạn cùng lên đường!
Người dịch.
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ĐOẠN MỞ ĐẦU
TRỞ LẠI NƯỚC TÍ HON

A-ra-ben-la

Ta-nhi-a, -va -.

,  
               

- -, -
- 



- 
             

-            
- 

l-va 
       

- 
A-ra-ben-la
T 

a

 



7
h









K


 

-va 
- 

- -va  
-va 
- 
- - Ta-nhi-a - 

 

- 
- 
- - -va - 

- - Ta-nhi-a - 

- 


- - Ta-nhi-a - 
8
- 



Ta-nhi-a 
- 
-va 
- -

- 
 -va      

Ta-nhi-a - 


-  

K

9


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- 
    
chu
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 
n 

- L
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



- 


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Ch 
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

 
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10
- 
K



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


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
-  - 


- - 
- 
- 
- - K-  


- 
- H
- - - 

- - K

  
 
.
11

- - - 
- 
- - 


- 


-  

 
- 



- 
- 

-  
-    
u.


- 
 
-          -     

12
- 
- - 
- 


           
 

- 


 
   
        
 

 


 

  
n 





             





 

13
  



               

-. - 

- 

- 
- - 
-      
 - -va 



K IPD CP IU OX T E UPK CK NCU
NP,U OX T IU D MK, OMPH T LMTPH UTA MK UPK
NPU OX T IU O XX MC, T E UPK MK DK EK IK
IU, D NPU IU DXQ H CK HL ULQK CA NC IK
UPK D CO OMKU IU? X RV EC
- 

      


- 
- - Ta-nhi-a 

- 
- 
Ta-nhi-a 
- 
14
- 
- - -va - 
- - Ta-nhi-a - 

- 




-va

 - 


- -, -
Con - 
  
-va
-va 

- 

- 

- 
- 

Ta-nhi-a 
- 
- 
- 

- 
15
- 


- 
- 
-  - Ta-nhi-a 

- 
-  
 
- 



   ,  ,    
.  ..  
U  O D., V   O

- -va 
- - Ta-nhi-- 

- - 
-  
  

 
- 
- 
- - -va 

- 
- 
-

16
- 
-  - -va -    

17
TRUY TÌM


A-ra-ben-la 




- - 


n

Tr



 




- 

 -


-va 
- -
- 

-va 
18
- 

- 
- 

- 
- 

Ta-nhi-a -:
- 
- 
.
-va 

- 
- - - Ta-nhi-a

- 
 

- - 

Ta-nhi-a  


- 
- - 
- - Ta-nhi-a  - 
nghe.

- 
- 
- 
19
- 
- 
- 

- . - -va 
- - 

- - 


- - - 

- 



20
NHỮNG BỨC THƯ
CHẶNG ĐƯỜNG HÀNH QUÂN
(Ô-lếch gửi Số Không)





nhau to.

 
 



      -va 



 




t
-
-

n






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
 
             

o
               
A-ra-ben-la 
-va 

XIN MỜI ĐẾN THĂM AN-GIÉP
Ta-nhi-a 

An- An- 






 
- 
 -va 
- 



-va



 -
 




Ô-lếch.
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NHỮNG NGƯỜI PHÀM ĂN
(Xê-va gửi Số Không)



 

An- 


An- 

HIỆP ƯỚC VĨ ĐẠI
VỀ TÌNH HỮU NGHỊ VÀ SỰ TƯƠNG TRỢ
ĐỜI ĐỜI GIỮA HAI CƯỜNG QUỐC
TÍ HON VÀ AN-GIÉP



 
h
 




.
              





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
  







     





              


- 


- 
- 
- 
- 





i



 
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












 

              






- - 
-  -     - 
 
Ta-nhi-a 


 


36
25
 


4


:


104




Ta-
nhi-a             
- 


- 
  

8 + 8
2
= 8


8.8 = 8
- 

 
 -  


 
- 
Ta-nhi-a 




4+2+1 = 7