Doug C. answered 04/26/22
Math Tutor with Reputation to make difficult concepts understandable
To find the x value that generates the maximum value for this function apply the 1st (or 2nd) derivative test.
f'(x) = 5cosx - 5xsinx
When does that equal zero?
That is where Newton's method comes into play.
You might want to think of this 1st derivative as g(x) = 5 cos(x) - 5xsin(x)
Find g'(x) and apply Newton's Method with x1 = π/2 (for example).
After applying Newton's Method you can use the 2nd derivative test to show that this is generating a maximum value for the original function, plug that value into the original to get the max value for "f" on the interval from 0 to π.