How many solutions are there for $x$ in the following equation: $$x^2 = -|x|.$$
I know that the absolute value of $x$ is always non-negative, and that $x^2$ is also non-negative for any real $x$. So the only way that $x^2$ can be equal to $-|x|$ is if they are both zero. That means $x$ has to be zero as well, since $|x| = 0$ only when $x = 0$. Therefore, there is only one solution for $x$ in this equation, which is $x = 0$. 