Question

Is it possible to factor `y= x^4 -3x^2 -4`? If so, what are the factors?

Answer 1

Yes. `x = +-2` or `x = +-i`

Explanation:

First represent the equation as a quadratic by substituting `z = x^2`
Then `y = z^2 -3z - 4`
This can be factored as `y = (z- 4)(z+1)`
Therefore `z = 4` or `z = -1`
Given `z =x^2` this means that `x = +-2` or `x = +- sqrt(-1) = +-i`