Finding zero of function problem please help

[marcuss]

Homework Statement

the function f(x)=tan(3^x) has one zero in the interval [0,1.4]. The derivative at this point is

The Attempt at a Solution

f'(x)= sec^2(3^x)*x3^(x-1) and i really cant seem to get a zero from that because i really dont know where to start and if im misinterpreting the problem please tell me that. Thanks

 

[whybother]

Wait, what is the initial question?
Are you trying to find roots of:

$$y=\tan{(3^x})$$
http://img7.imageshack.us/img7/7748/tan3x.jpg [Broken]

 

[whybother]

If that's the case, your derivative is incorrect.

$$f'(x) = 3^x \log(3) \sec^2({3^x})$$