Question 134
Let $A$ and $B$ be positive integers. Define the arithmetic row $a_{0}, a_{1}, a_{2}, \ldots$ by $a_{n}=A n+B$. Assume that there is at least one $n \geq 0$ so that $a_{n}$ is a square. They are $M$ a positive integer so that $M^{2}$ is the smallest squared in the row. Prove that $M\lt A+\sqrt{B}$.