How do use the first derivative test to determine the local extrema y = x + sinx?

Nov 8, 2015

Find values of x where $f ' \left(x\right) = 0$

Explanation:

$y ' = 1 + \cos \left(x\right) = 0$

$\cos \left(x\right) = - 1$ where $x = \pi \pm 2 \pi$

See graphic below: slope is zero at $\pi \pm 2 \pi$

hope that helped