Factorization

8xy - 15x^2 y^2 + 6x^3 - 20y^3
=( 6x^3 - 15x^2y^2) + (8xy - 20y^3)
= 3x^2( 2x - 5y^2) + 4y(2x - 5y^2)
= (3x^2 + 4)(2x - 5y^2)


2009-03-15 13:12:10 補充：
答案寫少左個y
(3x^2 + 4y)(2x - 5y^2)

Sorry!