试题

题目:
计算:
(多)
4
5
o2·(-
5
3
oy3)        
(2)(-3a32÷(-a)3
(3)(-3ab)(2a2-
3
ab+5b2
(4)o(
2
o+多)-3o(
3
2
o-2)

(5)(3a+b)(5a-2b)
(6)4o2-(2o-3y)(2o+3y)
(8)(-3ab2)(-a2c)2÷6ab2
(9)(o+多)(o-2)-(o-多)2
(多得)先化简,再求值:2o(o+多)-(3o-多)(2o-5),其中o=2.
答案
解:(1)
4
5
x2·(-
5
3
xy3)=-
4
5
×
5
3
x2·x·y3=
4
3
x3y3
(2)(-3a32÷(-a)3=9a6÷(-a3)=-9a3
(3)(-3ab)(2a2-
1
3
ab+5b2)=-6a3b+a2b2-15ab3
(4)x(
1
2
x+1)-3x(
3
2
x-2)
=
1
2
x2+x-
9
2
x2+6x=-4x2+7x;
(5)(3a+b)(5a-2b)=15a2-6ab+5ab-2b2=15a2-ab-2b2
(6)4x2-(2x-3y)(2x+3y)=4x2-(4x2-9y2)=4x2-4x2+9y2=9y2
(9)(-3ab2)(-a2c)2÷6ab2=(-3ab2)(a4c2)÷6ab2=-
1
2
a4c2
(9)(x+1)(x-2)-(x-1)2=(x2-x-2)-(x2-2x+1)=x2-x-2-x2+2x-1=x-3;
(10)2x(x+1)-(3x-1)(2x-5)=2x2+2x-(6x2-15x-2x+5)=2x2+2x-6x2+17x-5=-4x2+19x-5,
当x=2时,原式=-4×22+19×2-5=-16+39-5=17.
解:(1)
4
5
x2·(-
5
3
xy3)=-
4
5
×
5
3
x2·x·y3=
4
3
x3y3
(2)(-3a32÷(-a)3=9a6÷(-a3)=-9a3
(3)(-3ab)(2a2-
1
3
ab+5b2)=-6a3b+a2b2-15ab3
(4)x(
1
2
x+1)-3x(
3
2
x-2)
=
1
2
x2+x-
9
2
x2+6x=-4x2+7x;
(5)(3a+b)(5a-2b)=15a2-6ab+5ab-2b2=15a2-ab-2b2
(6)4x2-(2x-3y)(2x+3y)=4x2-(4x2-9y2)=4x2-4x2+9y2=9y2
(9)(-3ab2)(-a2c)2÷6ab2=(-3ab2)(a4c2)÷6ab2=-
1
2
a4c2
(9)(x+1)(x-2)-(x-1)2=(x2-x-2)-(x2-2x+1)=x2-x-2-x2+2x-1=x-3;
(10)2x(x+1)-(3x-1)(2x-5)=2x2+2x-(6x2-15x-2x+5)=2x2+2x-6x2+17x-5=-4x2+19x-5,
当x=2时,原式=-4×22+19×2-5=-16+39-5=17.
考点梳理
整式的混合运算;整式的混合运算—化简求值.
整式的混合运算顺序:先乘方,后乘除,最后算加减,有括号的先算括号里的;化简求值题,要先化简,再代入计算,可以使运算简便.
此题考查学生的计算能力,注意运算顺序、符号以及公式的运用.
找相似题