If x+2y+3z=0 then x3+8y3+27z3 = _____________
18xyz
Given that x+2y+3z=0
Hence x+2y=−3z
Taking cube on both sides, we have
(x+2y)3=(−3z))3
⇒(x)3+(2y)3+(3)(x)(2y)(x+2y)=(−27z3)
x+2y=−3z
⇒(x)3+(2y)3+(3)(x)(2y)(−3z)=(−27z3)
⇒(x3+8y3+(3)(x)(2y)(−3z)=(−27z3)
⇒(x3+8y3+27z3)=(3)(x)(2y)(3z)
=18xyz