2x+y=3且x-3y=5,则y(x-3y)^2+2x(3y-x)^2=?

问题描述:

2x+y=3且x-3y=5,则y(x-3y)^2+2x(3y-x)^2=?

y(x-3y)^2+2x(3y-x)^2
=y(x-3y)^2+2x(x-3y)^2
=(y+2x)(x-3y)^2
=3×5^2
=75