How do you factor $y=5x^4+10x^2-15$ ?

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Answer 1 · 2016-03-02T13:08:28

First factor you can take out is $5$

$=5(x^4+2x^2-3)$

Now if you see $x^2$ as a whole (let's call $x^2=z$ just for now) you have a quadratic expression you can factor further:
$=5(z^2+2z-3)=5(z+3)(z-1)$

Translated back, this becomes:
$=5(x^2+3)(x^2-1)$

And you can factor the last term even further:
$=5(x^2+3)(x-1)(x+1)$

How do you factor y=5x^4+10x^2-15y=5x^4+10x^2-15 ?