Help Me please.

But i think the answer is this:

-2,2,i√5,-i√5

is this correct?

x^4   + x^2 - 20  =  0      factor

(x^2 + 5) (x^2 - 4)  = 0

(x^2 + 5)  ( x - 2) ( x + 2)  = 0

Set each factor to 0...and solve for x

x  - 2  = 0       x +  2  = 0       x^2 + 5  = 0

x  =  2             x  =  -2           x^2  =  -5         take both roots

                                              x = ±√-5

                                              x  = ±√5 i

So....the solutions are

x  =   { -2, 2, √5 i ,  - √5 i    }

do I have to include the brackets in my answer?

Thank you Cphill

You are a Math saver!!