For the function f(x)= 5x-7sin(x), 0<x<pi
I need to find the open interval(s) f is increasing and decreasing on.
I first found the derivative which is 5-7cos(x) and then found the zeros of the function which is arccos(5/7)
From this I found the increasing open interval to be ((arccos(5/7)),inf) and decreasing open interval to be (-inf, (arccos(5/7)))
Somehow this is incorrect could someone tell me what I did wrong?
If your first derivative is positive then your function is increasing. If it is negative then your function is decreasing.
Originally Posted by ctran
So if we are in the interval 0 < x < acs(5/7) is your derivative positive or negative? If we are in the interval acs(5/7) < x < pi is your derivative positive or negative?