x+1分之x²加x+1分之2x+1,其中x=-2

问题描述:

x+1分之x²加x+1分之2x+1,其中x=-2
如题,顺手说下为什么这样做

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