# determine exact range

• Jun 18th 2011, 04:52 AM
Punch
determine exact range
Sketch the graph $y=\frac{x^3}{e^{ax}}$, hence determine the exact range of values of $a$ for which the equation $x^3=e^{ax}$

$x^3=e^{ax}$

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

$y=1$
• Jun 18th 2011, 06:22 AM
TKHunny
Re: determine exact range
That's a good start. I'm concered that the exponential is never zero or negative, quite unlike the other piece.
• Jun 19th 2011, 07:44 PM
ojones
Re: determine exact range
Your question isn't stated clearly. Are you asking for what values of $a$ is 1 is in the range of $y$? If so, graphing is not the way to do this. Better to differentiate to locate global extrema.