How do you factor x^4 + 64x4+64?

1 Answer
Apr 7, 2018

x^4+64 = (x^2-4x+8)(x^2+4x+8)x4+64=(x24x+8)(x2+4x+8)

Explanation:

Given:

x^4+64x4+64

Note that this is positive and therefore non-zero for any real value of xx. So it has no linear factors with real coefficients. We can find quadratic factors.

We can use the difference of squares identity to help with this:

A^2-B^2=(A-B)(A+B)A2B2=(AB)(A+B)

First note that:

(x^2+8)^2 = x^4+16x^2+64 = x^4+64+(4x)^2(x2+8)2=x4+16x2+64=x4+64+(4x)2

So:

x^4+64 = (x^2+8)^2-(4x)^2x4+64=(x2+8)2(4x)2

color(white)(x^4+64) = ((x^2+8)-4x)((x^2+8)+4x)x4+64=((x2+8)4x)((x2+8)+4x)

color(white)(x^4+64) = (x^2-4x+8)(x^2+4x+8)x4+64=(x24x+8)(x2+4x+8)