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kmekme100
Oct 4, 2009, 03:13 PM
factor fully

f(x) = x^4 - 5x^2 + 4

galactus
Oct 4, 2009, 05:05 PM
Let u=x^{2}

Then, we get u^{2}-5u+4

Now, factor the quadratic and resub.

u^{2}-5u+4=(u-4)(u-1)

Since u=x^{2}, resub:

(x^{2}-4)(x^{2}-1)

Note the difference of two squares in both.

(x+2)(x-2)(x+1)(x-1)