{1-x+2分之1}除以x²-4分之x²+2x+1跪求啊!

题目

{1-x+2分之1}除以x²-4分之x²+2x+1跪求啊!

答案

原式=[1-1/(x+2)]÷[(x²+2x+1)/(x²-4)]
=[(x+2)/(x+2)-1/(x+2)]÷{(x+1)²/[(x+2)(x-2)]}
=[(x+1)/(x+2)]×[(x+2)(x-2)/(x+1)²]
=(x-2)/(x+1)