SOLUTION: Find f ’(x) if f(x) = 3 x^3.9 - 6 x^-8.9 - 1 and evaluate f ’(1). (Keep 2 decimal places)

Hello,

I noticed that you submitted a number of requests similar to this one.

It looks like you are a student taking Calculus.

I will assume it in what follows.

Do you know what the derivative function is?

Do you know how to differentiate functions?

If not, look into your textbook and learn it from there.
Is is very basic skills and knowledge for a Calculus student.
Like adding and subtracting numbers for Elementary school students.
If you want to study Calculus, you must do it.

I don't know what is your textbook.
From my side, I'd recommend 
"Calculus of a single variable" by Larson and Edward, 5 edition, 2011,
ISBN 978-0-538-7355-0

You can buy it via Amazon for low cost (my was $8 plus delivery, Used at very good condition).

When you need to solve problems like this, you may use and you should know the standard table 
of derivatives of basic functions.
You may find such a table in the Internet. See, for example, these links

  http://tutorial.math.lamar.edu/pdf/Common_Derivatives_Integrals.pdf

  http://www.sosmath.com/tables/derivative/derivative.html