-4/（x^2-4）-1/（2-x）
=-4/(x+2)(x-2) + 1/(x-2)
=(-4+x+2)/(x+2)(x-2)
=(x-2)/(x+2)(x-2)
=1/(x+2)
x-7/（x-3）+1/(3-x)
=x - 7/(x-3) - 1/(x-3)
=(x^2-3x-7-1)/(x-3)
=(x^2-3x-8)/(x-3)第二题貌似错了(x-7)/（x-3）+1/(3-x)x-7 是分子吗?=(x -7)/(x-3) - 1/(x-3)=(x-7-1)/(x-3)=(x-8)/(x-3)