已知x-y=3,求代数式5-x+y+3(y-x)的值谢谢了,

问题描述:

已知x-y=3,求代数式5-x+y+3(y-x)的值谢谢了,

把x=y+3代入原式5-x+y=2,3(y-x)^3=-81,原式=-79