先化简再求值:(x2-x)/(x-1)*(x2-1)/(x2-2x+1)其中满足方程x2-3x+2=0

问题描述:

先化简再求值:(x2-x)/(x-1)*(x2-1)/(x2-2x+1)其中满足方程x2-3x+2=0

=x(x-1)/x-1×(x+1)(x-1)/(x-1)²
=x/x-1
方程可化为 (x-1)(x-2)=0
X1=1 X2=2
代入x/x-1得
①1/1-1,,,,分母为0无意义
②2/2-1-2
OK了,,

x²-3x+2=0
(x-1)(x-2)=0
因为分母x-1≠0
所以x-2=0
x=2
原式=x(x-1)/(x-1)*(x+1)(x-1)/(x-1)²
=x*(x+1)/(x-1)
=2*3/1
=6