How do you factor $x^{4} - 4 x^{2}$ $x^4-4x^2$ ?

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Answer 1 · 2016-11-15T09:04:56

$x^{4} - 4 x^{2} = (x^{2} + 2 x) (x^{2} - 2 x)$ $x^4 - 4x^2 = (x^2 +2x)(x^2 - 2x)$

These tell us that we are working with the Difference of Squares

The classic example states: $x^{2} - y^{2} = (x + y) (x - y)$ $" "x^2 -y^2 = (x+y)(x-y)$

$x^{4} - 4 x^{2} = (x^{2} + 2 x) (x^{2} - 2 x)$ $x^4 - 4x^2 = (x^2 +2x)(x^2 - 2x)$

The biggest difficulty is learning to recognise it for what it is.

Knowing some of the perfect squares by heart is a good start:

$149162536496481100121144$ $1" "4" "9" "16" "25" "36" "49" "64" "81" "100" "121" "144$

How do you factor x4−4x2x^4-4x^2?