你题目可能打错了,应该是2x+y=√3,x-3y=√2吧?
7y(x-3y)²-2(3y-x)³
=7y(x-3y)+2(x-3y)³
=(x-3y)²[7y+2(x-3y)]
=(x-3y)²(7y+2x-6y)
=(x-3y)²(2x+y)
=（√2）²×√3
=2√3