By applying Rolle's theorem, check whether it is possible that the function $f(x) = x^{5}+ x - 12$ has two real roots.

Answer: ? possible impossible

Your reason is that if $f(x)$ has two real roots then by Rolle's theorem, $f'(x)$ must be (input a number here) at certain value of $x$ between these two roots, but $f'(x)$ is always ? positive negative zero