Question

p^4-3p^2-18=0 ?

Answer 1

let p^2 = x

then its x^2 - 3x - 18 = 0

this factorises

(x - 6)(x+3) = 0

x = 6, -3

then p^2 = 6 and -3

\[p = \pm \sqrt{6}\]

and

\[p=\sqrt{-3}\]

or \[p = \pm i \sqrt{3}\]