先化简,再求值x-4/(x²-1)除以x²-3x-4/(x²+2x+1)+1/(x-1),其中x=2倍根号3+1
问题描述：
先化简,再求值x-4/(x²-1)除以x²-3x-4/(x²+2x+1)+1/(x-1),其中x=2倍根号3+1
x²-3x-4/(x²+2x+1)这个地方怎么化简?
答
x²-3x-4/(x²+2x+1)
=(x-4)(x+1)/(x+1)^2
=(x-4)/(x+1)