If anyone can help me with this problem, would be greatly appreciated.

Let b be $\displaystyle \mathbb R$ with b > 0 . Show that there exists a Cauchy sequence of Rational numbers {$\displaystyle \ a_n$} with $\displaystyle \ n \geq 1$ such that $\displaystyle \ a_n$ > 0 for all n of N and that $\displaystyle \ lim_{n -> \inf} a_n = b$