Question
Factorize the following expressions:
27x3 - y3 - z3 - 9xyz

Answer

We know that
x3 + y3 + z3 - 3xyz = ( x + y + z)(x2 + y2 + z2 - xy - yz -zx)
$\therefore$ 27x3 - y3 - z3 - 9xyz
= (3x)3 + (-y)3 + (-z)3 - 3(3x)(-y)(-z)
= [3x +(-y) + (-z)][(3x)2 + (-y)2 + (-z)2 - (3x)(-y)(-z)-(-z)(3x)]
= (3x - y - z)(9x2 + y2 + z2 + 3xy - yz + 3zx)

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