计算【1/(x-2)】-【1/(x+2)】+【(x2-4x)/(x2-4)】
问题描述:
计算【1/(x-2)】-【1/(x+2)】+【(x2-4x)/(x2-4)】
答
原式=[(x+2)-(x-2)]/(x+2)(x-2)+(x2-4x)/(x+2)(x-2)
=4/(x+2)(x-2)+(x2-4x)/(x+2)(x-2)
=(x2-4x+4)/(x+2)(x-2)
=(x-2)2/(x+2)(x-2)
==(x-2)/(x+2)