(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I've got two questions

1.Find the intervals on which f increases and and the intervals on which f decreases.

f(x)= x-cosx, 0≤x≤2∏

2. Why is f(x) = -2sin2x - 2sinx = -2sinx (2cosx + 1)

How can you factor 2cosx from the function on the left side?

2. Relevant equations

3. The attempt at a solution

1.I get f '(x) = 1 + sinx, 0≤x≤2∏

The answer says that it increases on [0,2∏] but I don't get it.

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# Homework Help: Increasing and descreasing function question

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