# Exercise 23.8 (v)

I was asked in class today about Ex. 23.8 (v) and gave some not so useful advice.  The problem asks you to prove that there is no positive integer solution to $x^2 +x +1 =y^2$.  There is a simple solution that begins with the observation that any positive solution would satisfy \$x < y\$, and so \$y \ge x+1\$ (since \$x\$ and \$y\$ are supposed to be integers).