How do you factor x^4 -3x^2 -4= 0?

1 Answer
May 19, 2016

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

Explanation:

Call x^2 = X, the trinomial transforms itself to -->
y = X^2 - 3X - 4.
Since a - b + c = 0, use shortcut.
The 2 factors are: (X + 1) and (X + c/a = X - 4).
y = (X + 1)(X - 4) = (x^2 + 1)(x^2 - 4) =
= (x^2 + 1)(x - 2)(x + 2)