先化简,再求值:2x+1-1x2-1÷xx2-2x+1,其中x=5.-数学

题目简介

先化简,再求值:2x+1-1x2-1÷xx2-2x+1,其中x=5.-数学

题目详情

先化简,再求值:
2
x+1
-
1
x2-1
÷
x
x2-2x+1
,其中x=5.
题型:解答题难度:中档来源:不详

答案

class="stub"2
x+1
-class="stub"1
x2-1
÷class="stub"x
x2-2x+1

=class="stub"2
x+1
-class="stub"1
(x+1)(x-1)
×
(x-1)2
x

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

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

=class="stub"x+1
x(x+1)

=class="stub"1
x
,(4分)
当x=5时,原式=class="stub"1
x
=class="stub"1
5
.(5分)

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