2x-y=-3,则（y-2x）的三次方-6x+3y+7的值为——,
问题描述：
2x-y=-3,则（y-2x）的三次方-6x+3y+7的值为——,
答
2x-y=-3
两边乘以 -1 *(2x-y) = -3 * -1
y-2x=3
(y-2x）^3-6x+3y+7
= (y-2x)^3 - 3(2x-y) +7
= 3^3 3 * (-3) +7
=27+9+7
=43