若a,b满足a²-3ab+2b²=6,且a-2b=3,则a-b等于(要过程!)

问题描述:

若a,b满足a²-3ab+2b²=6,且a-2b=3,则a-b等于(要过程!)

a²-3ab+2b²=(a-2b)(a-b)=6
那么a-b=(a²-3ab+2b²)/(a-2b)=6/3=2