x-y=3,求5-x+y+3(y-x)的平方

问题描述:

x-y=3,求5-x+y+3(y-x)的平方

5-x+y+3(y-x)的平方
=5-(x-y)+3(x-y)^2
=5-3+3*3^2
=2+27
=29