(1)计算:(-2)2-4+(13)-1-12sin30°(2)解方程:x-1x+1+2x1-2x=0.-数学

题目简介

(1)计算:(-2)2-4+(13)-1-12sin30°(2)解方程:x-1x+1+2x1-2x=0.-数学

题目详情

(1)计算:(-2)2-
4
+(
1
3
)-1
-
1
2
sin30°
(2)解方程:
x-1
x+1
+
2x
1-2x
=0
题型:解答题难度:中档来源:盐城模拟

答案

(1)(-2)2-
4
+(class="stub"1
3
)-1-class="stub"1
2
sin30°,
=4-2+3-class="stub"1
2
×class="stub"1
2

=5-class="stub"1
4

=class="stub"19
4


(2)方程两边都乘以(x+1)(1-2x)得,
(x-1)(1-2x)+2x(x+1)=0,
整理得,5x=1,
解得x=class="stub"1
5

检验:当x=class="stub"1
5
时,(x+1)(1-2x)=(class="stub"1
5
+1)(1-2×class="stub"1
5
)=class="stub"18
25
≠0,
所以,原分式方程的解是x=class="stub"1
5

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