Answer
$x=i\sqrt 3, -i\sqrt 3$
Work Step by Step
$x^4+2x^2-3=0$
$y=x^2$
$(x^2)^2+2x^2-3=0$
$y^2+2y-3=0$
$(y+3)(y-1)=0$
$(x^2+3)(x^2-1)=0$
$(x^2+3)(x+1)(x-1)=0$
$x+1=0$
$x=-1$
$x-1=0$
$x=1$
$x^2+3=0$
$x^2=-3$
$\sqrt {x^2} = \sqrt {-3}$
$x = \sqrt {3*-1}$
$x=i\sqrt 3$
$x=±i\sqrt 3$
