Find the value of $x$ such that $\sqrt{x+ 7} = 9$.
To solve for $x$, I need to isolate it on one side of the equation. To do that, I can start by squaring both sides, since that will undo the square root on the left. Squaring both sides gives me $(\sqrt{x + 7})^2 = 9^2$, which simplifies to $x + 7 = 81$. Now I can subtract 7 from both sides to get $x = 81 - 7$, which simplifies to $x = 74$. 