Prove that x + 1 is a factor of xn − 1 for every even number n.
Factor theorem says that for the polynomial p(x) and for the number a, if we have p(a) = 0, then (x − a) is a factor of p(x).
Given: Polynomial xn − 1
Divisor = (x + 1)
To check whether (x + 1) is a factor of xn − 1, we have to convert (x + 1) in a form that is suitable for the application of the Factor theorem.
(x + 1) = {x − (−1)}
Putting x = −1 in the given polynomial:
(−1)n − 1
= 1 − 1 { (−1)n = 1, for every even number n}
= 0
∴( x + 1) is a factor of the polynomial xn − 1 for every even number n.