Let G(x) be the generator polynomial used for CRC checking. The condition that should be satisfied by the G(x) to catch all errors consisting of an odd number of inverted bits is :
1
(x + 1) is factor of G(x)
2
(x ‐ 1) is factor of G(x)
3
(x2 + 1) is factor of G(x)
4
(1 ‐ x2) is factor of G(x)