Sketch the graph $\displaystyle y=\frac{x^3}{e^{ax}}$, hence determine the exact range of values of $\displaystyle a$ for which the equation $\displaystyle x^3=e^{ax}$

$\displaystyle x^3=e^{ax}$

$\displaystyle \frac{x^3}{e^{ax}}=1$

$\displaystyle y=1$