Question

What are all of the real roots of the following polynomial?

f(x) = x4 - 13x2 + 36

A.
-3, -1, 1, and 3
B.
-3 and 3
C.
-3, -2, 2, and 3
D.
-2 and 2

Answer 1

C. -3, -2, 2, and 3

Explanation:

x⁴ - 13x² + 36 = 0

(x²-4) (x²-9) = (x+2)(x-2)(x+3)(x-3) =0

x = 2 or x = -2 or x = 3 and or x = -3