What is the greater of the solutions to the equation $x^2 + 15x -54=0$?
To solve a quadratic equation, I can try to factor it, use the quadratic formula, or complete the square. Factoring seems easiest here, since I notice that $x^2 + 15x -54$ can be written as $(x+18)(x-3)$. So the equation becomes $(x+18)(x-3)=0$, which means that either $x+18=0$ or $x-3=0$. Solving for $x$, I get $x=-18$ or $x=3$. To find the greater solution, I compare these two values of $x$ and see that $x=3$ is greater than $x=-18$. Therefore, the greater solution is $x=3$. 