Question

Find the product of the following:
(x – 2y – z) (x2 + 4y2 + z2 + 2xy + zx -2yz )

Answer 1

Answer:

The product =x^3 - (2y)^3 - z^3 -6xyz

We know (a+b+c) (a^2 +b^2 +c^2 - ab-bc-ca) =

a^3 +b^3 +c^3 - 3abc

[x+(-2y)+(-z)] [x^2 +(-2y)^2 +(-z) ^2 - x(-2y)-(-2y)(-z)-(-z)x]=x^3 - 8y^3 - z^3 - 6xyz