Intervals of Increase and Decrease

The function is 3x-9sin(x), 0<x<pi

I found the derivative which is 3- 9cos(x)

Now how would I find the open intervals of increase and decrease given the domain 0<x<pi as seen above?

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Originally Posted by ctran

The function is 3x-9sin(x), 0<x<pi

I found the derivative which is 3- 9cos(x)

Now how would I find the open intervals of increase and decrease given the domain 0<x<pi as seen above?

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Set the derivative equal to 0. Figure out what angle corresponds to that in the domain of 0 to pi, as well as any possible repeats.

Quote:

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Originally Posted by Jameson

Set the derivative equal to 0. Figure out what angle corresponds to that in the domain of 0 to pi, as well as any possible repeats.

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I did this and found one angle which is arccosine(1/3), how would I go about finding other solutions within this domain?