1/1+x+2x/1-x²等于

问题描述:

1/1+x+2x/1-x²等于

1/1+x+2x/1-x²
=(x-1)/(x²-1)-2x/(x²-1)
=(x-1-2x)/(x+1)(x-1)
=-(x+1)/(x+1)(x-1)
=1/(1-x)