先化简,再求值:x+3/x-1乘x^2-2x+1/x^2+6x+9,其中x=-1/2

问题描述:

先化简,再求值:x+3/x-1乘x^2-2x+1/x^2+6x+9,其中x=-1/2

x+3/x-1乘x^2-2x+1/x^2+6x+9
=(x+3)/(x-1)乘(x-1)^2/(x-3)^2
=(x-1)/(x-3)
x=-1/2
原式
=(-3/2)/(-7/2)
=3/7