Question

(x+y)的平方 乘以 (x-y) 减去 (x+y) 乘以 (x-y)的平方等于多少？

Answer 1

(x+y)²×(x-y)-(x+y)(x-y)²
=(x+y)(x-y)[(x+y)-(x-y)]
=(x²-y²)×2y
=2x²y-2y³