题目列表(包括答案和解析)
20.已知x=5,y=4
,求代数式[-3
(x+y)] 3(x-y)·[-2(x-y)(x+y)]
2的值.
19.计算:
(1)(x-2y)(x+3y) (2)(x-1)(x2-x+1)
(3)(-2x+9y2)(x2-5y) (4)(2a2-1)(a-4)-(a2+3)(2a-5)
[综合创新训练]
18.当a=时,代数式(a-4)(a-3)-(a-1)(a-3)的值为( )
A. B.-10 C.10 D.8
17.计算结果是2x2-x-3的是( )
A.(2x-3)(x+1) B.(2x-1)(x-3)
C.(2x+3)(x-1) D.(2x-1)(x+3)
16.下列计算正确的是( )
A.(2x-5)(3x-7)=6x2-29x+35 B.(3x+7)(10x-8)=30x2+36x+56
C.(-3x+)(-
x)=3x2+
x+
D.(1-x)(x+1)+(x+2)(x-2)=2x2-3
15.判断:
(1)(a+3)(a-2)=a2-6 ( )
(2)(4x-3)(5x+6)=20x2-18 ( )
(3)(1+2a)(1-2a)=4a2-1 ( )
(4)(2a-b)(3a-b)=6a2-5ab+b2 ( )
(5)(am-n)m+n=am2-n2(m≠n,m>0,n>0,且m>n) ( )
14.计算:
(1)(a-3b)(-6a) (2)xn(xn+1-x-1)
(3)-5a(a+3)-a(3a-13) (4)-2a2(ab+b2)-5ab(a2-1)
13.x(y-z)-y(z-x)+z(x-y)的计算结果是( )
A.2xy+2yz+2xz B.2xy-2yz C.2xy D.-2yz
12.下列计算结果正确的是( )
A.(6xy2-4x2y)3xy=18xy2-12x2y
B.(-x)(2x+x2-1)=-x3-2x2+1
C.(-3x2y)(-2xy+3yz-1)=6x3y2-9x2y2z+3x2y
D.(an+1-
b)2ab=
an+2-ab2
11.若x(3x-4)+2x(x+7)=5x(x-7)+90,则x等于( )
A.-2 B.2 C.- D.
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