# Find the HCF

The HCF of x^{8}-1 and x^{4}+2x^{3}-2x-1 is

- x-1
- x
^{2}-1 - x+1
- x
^{2}+1

** Answer : (2) **x

^{2}-1

**Explanation : –
**Put the x = 1 and x = – 1

Then, The value of x

^{8}-1 is 0.

and the value of x

^{4}+2x

^{3}-2x-1 is 0.

Then, the H C F of x

^{8}-1 and x

^{4}+2x

^{3}-2x-1 is 0 is (x + 1) (x – 1).

Or (x + 1) (x – 1) = x

^{2}-1.

Hence, the answer is (2) x^{2}-1.