4x-12/x^2-4x-5除以2x-6/x^2-1除以(x-1),其中x=7 有些急,
问题描述：
4x-12/x^2-4x-5除以2x-6/x^2-1除以(x-1),其中x=7 有些急,
答
原式=4(x-3)/(x-5)(x+1)*(x+1)(x-1)/2(x-3)*(x-1)
=2/(x-5)(x-1)*(x-1)
=2/(x-5)
=2/(7-5)
=1