What are the real and complex solutions of the polynomial equation? 0=x^4+3x^2-4 a. -1,1 b. 1,2i c. -1,1,-2,2 d. -1,1,-2i, 2i

D. -1,1,-2i, 2i

Step-by-step explanation:

We should have 4 roots since this is a 4th degree polynomial.  We just have to watch since some of them may be multiple roots.

x^4+3x^2-4 = 0

Factoring this equation

(x^2 - 1) (x^2+4) = 0

We can factor the first term

(x-1) (x+1) (x^2+4) =0

Using the zero product property

x-1 =0  x+1 = 0  x^2+4 =0

x=1        x=-1        x^2 = -4

                            Taking the square root of each side

                           sqrt(x^2) =± sqrt(-4)

                                     x =± sqrt(-1) sqrt(4)

                                       x =±i *2

                                       x = ±2i