Question

Are 26 and 39 relatively prime

Answer 1

Use Euclid's algorithm:

39 = 1•26 + 13

26 = 2•13 + 0

The last remainder is not 1, so 26 and 39 are not relatively prime.

Alternatively, we have

26 = 2•13

39 = 3•13

so that GCD(26, 39) = 13 ≠ 1.