Question

Solve the following equation; give irrational answers in terms of surds.
$x^4+x^2-12=0$

Answer 1

$x^4+x^2-12=0$

$x^4+4x^2-3x^2-12=0$

$x^2(x^2+4)-3(x^2+4)=0$

$(x^2+4)(x^2-3)=0$

Now, $x^2+4=0x^2=-4\left(notpossible\right)$ Or $x^2-3=0x=\pm \sqrt{3}$

So, $x=+\sqrt{3},-\sqrt{3}$