Show That x(n) is a Cauchy Sequence for 0<r<1

[raw99]

If 0<r<1 and |x(n+1) - x(n)| < r ^n for all n. Show that x(n) is Cauchy sequence.
help please.

 

[dextercioby]

You may have at least written & used the definition of a Cauchy sequence...