5（a+b）²-3(2a+3b)-3(a+b)²+(2a+3b)=5(a+b)^2-6a-9b-3(a+b)^2+2a+3b=2 (-2 a + a^2 - 3 b + 2 a b + b^2)(x-6)²+|y+1|=0,x=6y=-1﹙﹣x+2y/3﹚-2/3（x+1/2y）=(-6-2/3)-2/3(6-1/2)=-(31/3)