Question

Need help on question 17

Answer 1

x = - 1 or 1 or -4 or 4

Explanation:

x^4 - 17x^2 + 16 = 0

let y = x^2

y^2 -17y + 16 = 0

(y-16)(y-1) = 0

y = 16 or y = 1

x^2 = 16 or x^2 = 1

x^2 = 16: x = 4 or -4

x^2 = 1: x = 1 or -1