(x+1-x-1分之15)÷x+1分之x-4

问题描述:

(x+1-x-1分之15)÷x+1分之x-4

原式=[(x+1)(x-1)/(x-1)-15/(x-1)]÷[(x-4)/(x+1)]
=[(x²-1-15)/(x-1)]×[(x+1)/(x-4)]
=(x+4)(x-4)(x+1)/[(x+1)(x-4)]
=x+4