Question

因式分解：（x+y+z)的立方-x的立方-y的立方-z的立方

Answer 1

(x+y+z)³-x³-y³-z³

=（y+z)[(x+y+z)²+x(x+y+z)+x²]-(y+z)(y²-yz+z²)

=(y+z)(3x²+3xy+3xz+3yz)

=3（y+z)(x+y)(x+z)