Question

three roots of the polynomial equation x^4 - 4x^3 - 2x^2 +12x + 9 = 0 are 3, -1 and -1. Explain why the fourth root must be a real number. Find the fourth root.

Answer 1

@Kamauri
@bill533
@Elsa213
@Eiwoh2

Answer 2

i got some help

Answer 3

@Kayden
Thank You :)

Answer 4

complex roots come in pairs, so there can't just be 1 complex root. therefore the missing root must be real.

the given roots are 3, -1, and -1 which means you can divide the original polynomial by (x-3)(x+1)(x+1) using polynomial division to find the missing roots

Answer 5

thank you :)