## anonymous 5 years ago Some determine for me the roots x^4 +6x^2 -27=0

1. anonymous

make substitution x^2=y then the eqn. is (y+9)(y-3)=0 which gives x=+rt(3),-rt(3),3i,-3i

2. anonymous

$x^4+6x^2-27=(x^2+9)(x^2-3)=0$

3. anonymous

are you working with complex numbers or just real? if real the answers are $\pm \sqrt{3}$

4. anonymous

real no.s

5. anonymous

oops sorry saubhik got it already

6. anonymous

oh well in real numbers $x^2+9=0$ has no solution because if you write $x^2=-9$ you are looking for a real number whose square is negative and there isn't one.