Bài kiểm tra môn Đại số 8 tiết 21 - Trường THCS Đông Sơn

<span class='text_page_counter'>(1)</span>Trường THCS đông sơn Líp: 8 Hä tªn: ……………….……………………….. Thø. , ngµy. th¸ng. n¨m 2009. Bài kiểm tra môn đại số §Ò lÎ Thêi gian: 45 phót. §iÓm. Lêi phª cña c« gi¸o. Bài 1: Khoanh tròn vào chữ đứng trước câu trả lời đúng: (3 điểm) 1. KÕt qu¶ phÐp tÝnh nh©n -xy.(2x2 - 3xy + y2) lµ: A. - 2x3y - 3x2y2 + xy3 B. 2x3y - 3x2y2 + xy3 C. - 2x2y + 3x2y2 - xy2 D. - 2x3y + 3x2y2 - xy3 2. KÕt qu¶ phÐp tÝnh nh©n (x + 1)(x2 + 2x - 1) lµ: A. x3 + x2 + 3x - 1 B. x3 + 2x2 + x - 1 C. x3 + 3x2 + x - 1 D. x3 - x2 + x - 1 2. 1 3. KÕt qu¶ phÐp tÝnh   2 y  lµ: 2  1 1 A.  4 y 2 B.  4 y  4 y 2 4 4. C.. 1  2 y  4 y2 4. D.. 1  2 y  2 y2 4. 4. KÕt qu¶ ph©n tÝch ®a thøc x(x - y) - (x - y) thµnh nh©n tö lµ: A. (x - y)x B. (x - y)(x - 1) C. (x - y)(x + 1) D. Cả 3 đáp án trên đều đúng. 5. KÕt qu¶ ph©n tÝch ®a thøc (x - y)2 - 1 thµnh nh©n tö lµ: A. (x + y - 1)(x - y - 1) B. (x - y + 1)(x - y - 1) C. (x - y - 1)(x - y - 1) D. Kh«ng ph©n tÝch ®­îc thµnh nh©n tö. 2 2 6. KÕt qu¶ phÐp chia ®a thøc (4x - 9y ) : (2x + 3y) lµ: A. 2x + 3y B. 2x - 3y C. 2x2 - 3y2 D. Kh«ng chia hÕt Bài 2: (2 điểm) Điền vào chỗ ………… trong các khẳng định sau: 1. Muốn nhân một đơn thức với một đa thức, ta nhân đơn thức với …………………... ………………………………… råi …………………………………………………………………. 2. Muèn nh©n mét ®a thøc víi mét ®a thøc, ta nh©n …………………………………....….. cña ®a thøc nµy víi …………………………………... cña ®a thøc kia råi ……………… ………………………………………………………………………………………………………….. 3. Muốn chia đa thức A cho đơn thức B, ta chia …………………………………....……….. råi …………………………………...………………………………………………………………... 4. Phân tích đa thức thành nhân tử (hay thừa số) nghĩa là biến đổi đa thức đó trở thµnh …………………………………....………..…………………………………...……………… Bµi 3: (2 ®iÓm) Rót gän biÓu thøc sau: a) x2 - 4 - (x + 4)(x - 4) b) x2 + (1 - 2x)2 + 2(1 - 2x)x Bµi 4: (2 ®iÓm) Ph©n tÝch c¸c ®a thøc sau thµnh nh©n tö: 2. a). x3 -. 6x2 +. 12x - 8. 1 b)  x    (2 x  1) y  y 2 2  Lop8.net.

<span class='text_page_counter'>(2)</span> Bµi 5: (1 ®iÓm) T×m x, biÕt: (x - 3)2 - (3 + x)(x - 3) ..................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................... 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Lop8.net.

<span class='text_page_counter'>(3)</span> Trường THCS đông sơn Líp: 8 Hä tªn: ……………….……………………….. Thø. , ngµy. th¸ng. n¨m 2009. Bài kiểm tra môn đại số §Ò ch½n Thêi gian: 45 phót. §iÓm. Lêi phª cña c« gi¸o. Bài 1: (2 điểm) Điền vào chỗ ………… trong các khẳng định sau: 1. Muèn nh©n mét ®a thøc víi mét ®a thøc, ta nh©n …………………………………....….. cña ®a thøc nµy víi …………………………………... cña ®a thøc kia råi ……………… ………………………………………………………………………………………………………….. 2. Muốn nhân một đơn thức với một đa thức, ta nhân đơn thức với …………………... ………………………………… råi …………………………………………………………………. 3. Phân tích đa thức thành nhân tử (hay thừa số) nghĩa là biến đổi đa thức đó trở thµnh …………………………………....………..…………………………………...……………… 4. Muốn chia đa thức A cho đơn thức B, ta chia …………………………………....……….. råi …………………………………...………………………………………………………………... Bài 1: Khoanh tròn vào chữ đứng trước câu trả lời đúng: (3 điểm) 1. KÕt qu¶ phÐp tÝnh nh©n -xy.(2x2 - 3xy + y2) lµ: A. - 2x3y - 3x2y2 + xy3 B. - 2x3y + 3x2y2 - xy3 C. - 2x2y + 3x2y2 - xy2 D. 2x3y - 3x2y2 + xy3 2. KÕt qu¶ phÐp tÝnh nh©n (x + 1)(x2 + 2x - 1) lµ: A. x3 + x2 + 3x - 1 B. x3 + 2x2 + x - 1 C. x3 - x2 + x - 1 D. x3 + 3x2 + x - 1 2. 1 3. KÕt qu¶ phÐp tÝnh   2 y  lµ: 2  1 1 A.  2 y  4 y 2 B.  4 y  4 y 2 4 4. C.. 1  2 y  2 y2 4. D.. 1  4 y2 4. 4. KÕt qu¶ ph©n tÝch ®a thøc x(x - y) - (x - y) thµnh nh©n tö lµ: A. (x - y)x B. (x - y)(x + 1) C. (x - y)(x - 1) D. Cả 3 đáp án trên đều đúng. 5. KÕt qu¶ ph©n tÝch ®a thøc (x - y)2 - 1 thµnh nh©n tö lµ: A. (x - y + 1)(x - y - 1) B. (x + y - 1)(x - y - 1) C. (x - y - 1)(x - y - 1) D. Kh«ng ph©n tÝch ®­îc thµnh nh©n tö. 6. KÕt qu¶ phÐp chia ®a thøc (4x2 - 9y2) : (2x + 3y) lµ: A. 2x2 - 3y2 B. 2x + 3y C. 2x - 3y D. Kh«ng chia hÕt Bµi 3: (2 ®iÓm) Rót gän biÓu thøc sau: a) x2 - 5 - (x + 5)(x - 5) b) x2 + (1 - 3x)2 + 2(1 - 3x)x Bµi 4: (2 ®iÓm) Ph©n tÝch c¸c ®a thøc sau thµnh nh©n tö: 2. a) x3 + 6x2 + 12x + 8. 1 b)  x    (2 x  1) y  y 2 . Lop8.net. 2.

<span class='text_page_counter'>(4)</span> Bµi 5: (1 ®iÓm) T×m x, biÕt: (x - 5)2 - (5 + x)(x - 5) ..................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................... 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Lop8.net.

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