Question

设A=2x²-3xy+y²+x-3y ,B=4x²-6xy+2y²+4x-y ,

Answer 1

a=4x²-6xy+2y²+4x-y-2(2x²-3xy+y²+x-3y)=2x+5y

两项都是大于等于0,所以两项都是0.a+8x=10x+5y=0；y+1=0.所以y=-1,x=0.5,a=-4

A=5.5；B=9