一、填空题
1．(a+b)(m+n) =______.
2．二项式与三项式相乘,在未合并同类项之前,积的项数为________.
3．(x+2)(x–1) =__________; (a–3)(a–4) =________.
4．(x+a)(x+b) =________.
5．(2x–3)(2x+1) =________.
6．(3m–n)(3m+n–1) =________.
7．(x+____ )(x–____) = x2 –7x –18;
(____+2)(3xy–____) =9x2y2 –9xy –10.
8．(a+b)(a2 –ab+b2) =________.
9．(x –y) 2 = (x –y)(x –y) =________.
10．应用第9题,计算(x –y) 3 =________.
二、判断正误(正确的划“√”,错误的划“╳”)
1．(x+1)(x –2) = x2 –3x –2.( )
2．(a –b)(m–n) = am +an –bm –bn.( )
3．(a –b) 2 = a2 –2ab+b2.( )
4．(2a –1)(1+2a) = 4a2 +4a –1.( )
5．(x –4)(y –3) =x2 –7x+12.( )
6．(3x –2y)(3x+4y) = 9x2 +2xy –8y.( )
三、选择题（请将正确答案前的字母填入括号内）
1．(x+5)(x –7)的计算结果是（ ）.
(A) x2 –12x –35 (B) x2+12x –35
(C) x2 –2x –35 (D) x2 +2x –35
2．下列各式中,结果错误的是（ ）.
(A) (x+2)(x –3) =x2 –x –6 (B) (x –4)(x+4) = x2– 16
(C) (2x +3)(2x –6) = 2x2 –3x –18 (D) (2x –1)(2x+2) =4x2 +2x –2
3．(3x+5a)(a –3x)的计算结果是 ( ).
(A) 9x2 +12ax –5a2 (B) 9x2 –12ax –5a2
(C) 9x2 –12ax +5a2 (D) –9x2 –12ax +5a2
4．(x –a)(x2+ax +a2) 的计算结果是 ( ).
(A) x3 +2ax2 –a3 (B) x3 –a3
(C) x3 +2a2x –a3 (D) x2 +2ax2 +2a2 –a3
5．下列各式中,正确的是（ ）.
(A) (2xy –1)(xy –3) =2x2y2 –4xy +3
(B) (2m –n)(n+2m) = 4m2 –2mn –n2
(C) (y –1)(y+1) (2y2+1) =2y4 –3y2 –1
(D) (x –3)(x –1) (x+1) =x3–3x2–x+3
6．三个连续奇数,最小的一个为n,则它们的积为（ ）.
(A) n3 +6n2 +8n (B) n3 +3n2 +2n
(C) n3+8n3 +6n (D) n3 –4n
四、计算题
1．(x+2)(x+2)
2．(x2 +3x –1)(x +1) – (x2 –2)(x –4)
3．(3x3 –8x2 –2x +20)(x2 +x –1)
五、解方程
(x –1)(x+1) = (x +2)(x –2) +x
参考答案
一、1．am +an +bm +bn； 2.6；
3．x2 +x –2,a2 –7a +12；
4．x2 +(a +b) x +ab；
5．4x2 –4x –3；
6．9m2 –3m –n2 +n；
7．2,9; 3xy,5; 8.a3 +b3;
9.x2 –2xy +y2
10．x3 –3x2y +3xy2 –y3;
二、1.╳；2.╳；3.√；4.╳；5.╳；6.╳.
三、1.(C)；2.(C)；3.(D)；4.(B)；5.(D)；6.(A).
四、1.x2 +4x +4； 2.8x2 +4x –9; 3.3x5 –5x4 –13x3 +26x2 +22x –20.
五、1．x =3.