Question

9(x+y+z)²-(x-y-z)²

分解因式 9（x+y+z)²-（x-y-z)²
答案是4（2x+y+z)(x+2y+2z) 我想要过程，谢谢

Answer 1

9（x+y+z)²-（x-y-z)²
=[3(x+y+z)-x+y+z][3(x+y+z)+x-y-z]
=(3x+3y+3z-x+y+z)(3x+3y+3z+x-y-z)
=(2x+4y+4z)(4x+2y+2z)
=4(x+2y+2z)(2x+y+z)