# Solving for x involving trig

1. Nov 13, 2009

### kpou

I have formula z(x)=2ASin(7*pi*x)Cos(3*pi*x)
I need to find the location where the displacement is max and min.

I understand how to get the differential z'(x)=A4piCos(4*pi*x)+A10piCos(10*pi*x)
Then I need to find critical points... this is where I have been having the trouble. My calculator keeps telling me my dimensions don't work, and it is really killing me. How do you solve for that = 0?

Edit: z(x) can also be written as A(Sin(4*pi*x)+Sin(10*pi*x)) if that saves you any work
Also: x is between 0 and 1meter

-----------Problem Solved----------

Last edited: Nov 13, 2009