Maclaurin Serial question

[brsf4]

With the help of Maclaurin serial expansion lncos(9x) , find the first four terms that are different from zero ?

Is there anyone who can solve this question?

 

[Dr.Peterson]

With the help of Maclaurin serial expansion lncos(9x) , find the first four terms that are different from zero ?

Is there anyone who can solve this question?

Apparently you are expected to be able to. Can you at least start?

What have you learned about finding Maclaurin series? Or, if you know nothing, what have you been taught?

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[brsf4]

Apparently you are expected to be able to. Can you at least start?

What have you learned about finding Maclaurin series? Or, if you know nothing, what have you been taught?

Please follow our guidelines:

Posting Guidelines (Summary)

Welcome to our tutoring boards! :) This page summarizes main points from our posting guidelines. As our name implies, we provide math help (primarily to students with homework). We do not generally post immediate answers or step-by-step solutions. We don't do your homework. We prefer to help...

www.freemathhelp.com

I'm asking because I couldn't solve it.

 

[Steven G]

We understand that you can't solve but can you at least start it? We are not here to solve your problem, as that will not be helpful, rather we are here to help you solve your problem.

Can you at least state the formula for Maclaurin series and try to follow it. If you make a mistake we will point it out. You can do it!

 

[HallsofIvy]

And, by the way, it is "Maclaurin series", not "serial". For a function, f, the Maclaurin series is \(\displaystyle f(0)+ f'(0)x+ \frac{f''(0)}{2}x^2+ \cdot\cdot\cdot+ \frac{f^{(n)}(0)}{n!}x^n+ \cdot\cdot\cdot\).

Here, f(x)= ln(cos(x)). What is f(0)? What is f'(x)? What is f'(0)? Etc.