解：∵2x+y=6 x-3y=1 ∴3y-x=-1 ∴7y(x-3y)²-2(3y-x)³ =7y(3y-x)²-2(3y-x)³ =(3y-x)²(7y-6y+2x) =(3y-x)²(y+2x) =(-1)²×6 =6
