合并同类项并求值:(x-y)2+7(x+y)-11(x-y)2-8(x+y),其中x=6,y=1.
问题描述:
合并同类项并求值:(x-y)2+7(x+y)-11(x-y)2-8(x+y),其中x=6,y=1.
答
原式=-10(x-y)2-(x+y)=x2-2xy+y2+7x+7y-11x2+22xy-11y2-8x-8y=-10x2+20xy-10y2-x-y,
当x=6,y=1时,原式=-360+120-10-6-1=-257.