(x-y)的七次方/(y-x)的三次方/(y-x)的三次方
= -(y-x)的七次方/(y-x)的三次方/(y-x)的三次方
= -(y-x)
(4x+3y)的平方-(3x-4y)的平方
(4x+3y)^2-(3x-4y)^2
=((4x+3y)+(3x-4y))((4x+3y)-(3x-4y))
=(7x-y)(x+7y)
(x-y)的七次方/(y-x)的三次方/(y-x)的三次方
= -(y-x)的七次方/(y-x)的三次方/(y-x)的三次方
= -(y-x)
(4x+3y)的平方-(3x-4y)的平方
(4x+3y)^2-(3x-4y)^2
=((4x+3y)+(3x-4y))((4x+3y)-(3x-4y))
=(7x-y)(x+7y)