first time asking a question here.
This proof seems simple, but the only part throwing me off is the the first two remarks "Show that for every positive integer a, there exist a positive integer $b$ such that $ab+1$ is a perfect square."
What I have is: Let $k = n^2$ where is an integer and $n^2$ is perfect square. then $ab+ 1 = k $
This is where I get stuck.