问题 解答题 若x,y满足2x+y=6x-3y=1,求7y(x-3y)2-2(3y-x)3的值. 答案 7y(x-3y)2-2(3y-x)3,=7y(x-3y)2+2(x-3y)3,=(x-3y)2[7y+2(x-3y)],=(x-3y)2(2x+y),当2x+y=6x-3y=1时,原式=12×6=6.