How do you factor $y=x^3 + 6x^2 + 8x$ ?

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Answer 1 · 2016-07-22T19:56:33

$y = x(x+2)(x+4)$

Take common factor of x out leaving a quadratic inside:

$y = x(x^2+6x + 8)$

Fairly easy to solve by eye but will use quadratic formula for completeness:

$x = (-6+-sqrt(6^2 - 4*1*8))/2 = (-6+-sqrt(4))/2$

$implies x = -2 or x = -4$

Hence

$y = x(x+2)(x+4)$

How do you factor y=x^3 + 6x^2 + 8x y=x^3 + 6x^2 + 8x ?