计算（1-x+2分之1）÷x²-4分之x²+2x+2
问题描述：
计算（1-x+2分之1）÷x²-4分之x²+2x+2
答
原式=(x+2-1)/(x+2)*(x²-4)/(x²+2x+1)
=(x+1)/(x+2)*(x+2)(x-2)/(x+1)²
=(x-2)/(x+1)