B
丢掉了分母
(x-3)/(x²-1)-2/(1+x)
=(x-3)/(x+1)(x-1)-2(x-1)/(x+1)(x-1)(A)
=[x-3-2(x-1)] /(x+1)(x-1) (B)
=(x-3-2x+2)//(x+1)(x-1) (C)
=(-x-1)/(x+1)(x-1) (D)
=-(x+1)/(x+1)(x-1)
=-1/(x-1)
=1/(1-x)
B
丢掉了分母
(x-3)/(x²-1)-2/(1+x)
=(x-3)/(x+1)(x-1)-2(x-1)/(x+1)(x-1)(A)
=[x-3-2(x-1)] /(x+1)(x-1) (B)
=(x-3-2x+2)//(x+1)(x-1) (C)
=(-x-1)/(x+1)(x-1) (D)
=-(x+1)/(x+1)(x-1)
=-1/(x-1)
=1/(1-x)