Well, I got this equation [itex]f(x)=\frac{2\sin{2x}}{x}[/itex] [itex] [-\pi,\pi][/itex](adsbygoogle = window.adsbygoogle || []).push({});

So I took the 1st derivative, [itex]f'(x)=\frac{2(2x\cos{2x} - \sin{2x})}{x^2}[/itex]

Then I set that equal to 0, and got [itex]0=2x\cos{2x} - \sin{2x}[/itex]

But I do not see how to get the critical numbers, I also tried to do double angle, but that just resulted in more pain.

Any help, would be appreciated.

edit: Can an mod please remove this post, seems I posted in the wrong section. :(

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Finding Critical Numbers

**Physics Forums | Science Articles, Homework Help, Discussion**