使(ax²-2xy+y²)-(-ax²+bxy+2y²)=6x²-9xy+cy²成立的a、b、c的值是

问题描述:

使(ax²-2xy+y²)-(-ax²+bxy+2y²)=6x²-9xy+cy²成立的a、b、c的值是

(ax²-2xy+y²)-(-ax²+bxy+2y²)
=2ax²-(2+b)xy-y²
=6x²-9xy+cy²
故:2a=6;2+b=9;-1=c
故:a=3;b=7;c=-1