Find all the solutions to the given polynomial. x^4+x^2-20=0

1: Factor the problem
    (x^2+5)(x^2-4)=0
2: Set each equal to 0
     x^2+5=0
     x^2-4=0
3: Solve Each
    x^2=-5
    - Cannot take square root of a negative, therefore extraneous
    x^2=4
    x= 2, -2

Find all the solutions to the given polynomial. x^4+x^2-20=0 x^2+5=0
     x^2-4=0, x^2=-5

x^2=4
    x= 2, -2