cos2xcosx化简 先化简分式[（3x/x-1)-(x/1+x）]/(x/1-x²）

先化简分式[（3x/x-1)-(x/1+x）]/(x/1-x²）  

先化简分式[（3x/x-1)-(x/1+x）]/(x/1-x²）

x-3x+6≥2
x≤2
4x-2<5x+1
x>-3
-3<x≤2
原式=[3x(x+1)-x(x-1)]/(x-1)(x+1)×(1-x²)/x
=-(3x²+3x-x²+x)/(1-x²)×(1-x²)/x
=-(2x²+4x)/x
=-2x-4
分母不等于0
所以取x=2
原式=-4-4=-8

先化简分式(3x/x-1 -x/x-1)÷x/x平方-1，再在-3＜x≤2范围内取一个合适的数字代入

化简:(3x/x-1 -x/x-1)÷x/x²-1=2x/(x-1)]*[(x+1)(x-1)/x]=2(x+1),
在-3＜x≤2范围内，因为x≠0,和±1,取x=2,代入，原式＝6，
若取x=-2代入，则 原式＝-2。

化简分式【(x/x+1)+(x/x^2-1)】/(x^2+x/x^2+2x+1)

解：
[(x/x+1)+(x/x²-1)]/(x²+x/x²+2x+1)
=[x(x-1)/(x²-1)+x/(x²-1)]/[x(x+1)/(x+1)²]
=x²/(x²-1)/[x/(x+1)]
=x/(x-1)
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化简分式 （1）x²+x/x²-1 （2）x²-9/x²-6x+9

x²+x/x²-1 =x(x+1)/(x+1)(x-1)=x/(x-1)
x²-9/x²-6x+9 =(x+3)(x-3)/(x-3)^2=(x+3)/(x-3)

化简 （3x/x-1 -x/x+1）÷x/x²-1

=【3x(x+1)-x(x-1)]/(x+1)(x-1) ×(x+1)(x-1)/x
=(3x²+3x-x²+x)/x
=4

3x/x-1-2(1+1/x-1)²=x/x+1的结果 3x/x-1-2(1+1/x-1)²=x/x+1的结果

两边乘(x-1)²(x+1)
3x(x+1)(x-1)-2x²(x+1)=x(x-1)²
3x³-3x-2x³-2x²=x³-2x²+x
-3x=x
x=0

化简分式[x/(x+1)-2/(x^2-1)]÷(x^2-4)/(x^2-2x+1)

解
原式
=[x(x-1)/(x-1)(x+1)-2/(x+1)(x-1)]÷(x-2)(x+2)/(x-1)²
=[(x²-x-2)/(x-1)(x+1)]×(x-1)²/(x-2)(x+2)
=(x-2)(x+1)/(x-1)(x+1)×(x-1)²/(x-2)(x+2)
=(x-2)/(x-1)×(x-1)²/(x-2)(x+2)
=(x-1)/(x+2)

化简(1/x-1 - 1/x1)/ x/2x²²-2

(1/x-1 - 1/x1)/ x/2x22-2
=(x/x2-x - x-1/x2-x ) × 2x2-2/x
=1/x2-x × 2x2-2/x
=1/x(x-1) ×2(x-1)(x+1)
=2(x+1)/x2
=2x+2/x2

[﹙x/x+1﹚+1]÷[1-﹙3x²/1-x²﹚]×﹙1/x-1﹚，其中x=4的负1次方？

x=4^(-1)
x=1/4
[x/(x+1)+1]÷[1-3x²/(1-x²)]×1/(x-1)
=[x/(x+1)+1]÷[1+3x²/(x²-1)]×1/(x-1)
=[(x+x+1)/(x+1)]÷[(x²-1+3x²)/(x²-1)]×1/(x-1)
=[(2x+1)/(x+1)]÷[(4x²-1)/(x²-1)]×1/(x-1)
=(2x+1)/(x+1)×(x²-1)/(4x²-1)×1/(x-1)
=(2x+1)/(x+1)×(x-1)(x+1)/(2x-1)(2x+1)×1/(x-1)
=(2x+1)/(x+1)×(x+1)/(2x-1)(2x+1)
=(2x+1)×1/(2x-1)(2x+1)
=1/(2x-1)
=1/(2*1/4-1)
=1/(-1/2)
=-2

先化简,再求值:（x²-1）/（x²+2x+1）÷（x-1）/（x+1）-x/（x+1），其中x=根号2-1

（x²-1）/（x²+2x+1）÷（x-1）/（x+1）-x/（x+1），其中x=根号2-1
=(x-1)(x+1)/(x+1)²÷(x-1)/(x+1)-x/(x+1)
=(x-1)/(x+1)÷(x-1)/(x+1)-x/(x+1)
=1-x/(x+1)
=(x+1-x)/(x+1)
=1/(x+1)
=1/(√2-1+1)
=1/√2
=√2/(√2*√2)
=1/2(√2)