解
(2x+y-3z)²-(2x-y+3z)²
=[(2x+y-3z)+(2x-y+3z)][(2x+y-3z)-(2x-y+3z)]
=(2x+y-3z+2x-y+3z)(2x+y-3z-2x+y-3z)
=4x(2y-6z)
=8x(y-3z)