计算:(1)x-2x+3•x2-9x2-4;(2)3x-4-24x2-16;(3)12x-1x+y•(x+y2x-x-y).-数学

题目简介

计算:(1)x-2x+3•x2-9x2-4;(2)3x-4-24x2-16;(3)12x-1x+y•(x+y2x-x-y).-数学

题目详情

计算:
(1)
x-2
x+3
x2-9
x2-4

(2)
3
x-4
-
24
x2-16

(3)
1
2x
-
1
x+y
•(
x+y
2x
-x-y)
题型:解答题难度:中档来源:不详

答案

(1)原式=class="stub"x-2
x+3
(x+3)(x-3)
(x+2)(x-2)

=class="stub"x-3
x+2


(2)原式=class="stub"3
x-4
-class="stub"24
(x+4)(x-4)

=
3(x+4)-24
(x+4)(x-4)

=class="stub"3x-12
(x+4)(x-4)

=class="stub"3
x+4


(3)原式=class="stub"1
2x
-class="stub"1
x+y
(x+y)(1-2x)
2x

=class="stub"1
2x
-class="stub"1-2x
2x

=class="stub"1-1+2x
2x

=1.

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