Chapter 4.5, Problem 236E

For the following exercises, determine

1. intervals where f is increasing or decreasing,
2. local minima and maxima of f,
3. intervals where f is concave up and concave down, and
4. the inflection points of f. Sketch the curve, then use a calculator to compare your answer. If you cannot determine the exact answer analytically, use a calculator.

236. [T] $f\left(x\right)=\frac{\sin x}{x}$ over $x=\left[-2\pi ,2\pi \right]\left[2\pi ,0\right)\cup \left(0,2\pi \right]$