What is the HCF of 8 (N 5 - N 3 + N ) and 28 (N 6 + 1)?

Let p(N) = 8 (N⁵ - N³ + N)
= 4 x 2 x N (N⁴ - N² + 1)
and q(N) = 28 (N⁶ + 1)
= 7 x 4 [( N²)³ + (1)³]
= 4 x 7 (N² + 1) ( N⁴ - N² + 1)
∴ HCF of p(N) and q (N) = 4 (N⁴ - N² + 1)