Dummit and Foote exercise 17 Section 1.2 Dihedral Groups reads as follows:

Let $\displaystyle X_{2n}$ be the group whose presentation is

$\displaystyle X_{2n}$ = <x,y | $\displaystyle x^n$ = $\displaystyle y^2$ = 1, xy = y$\displaystyle x^2$>

Show that if n = 3k, then $\displaystyle X_{2n}$ has order 6, and it has the same generators and relations as $\displaystyle D_6$ when x is replaced by r and y is replaced by s.

Can anyone help with this problem?

Can anyone with some insight into this problem guess what D&F meant by n = 3k - would it mean n is a multiple of 3 - that is k is a positive integer? I presume they mean this.