Determine Where the Graph of the Function $f(x)=\sin 9 x$ Is Concave Upward and Where It Is Concave Downward on Is

Short Answer

Determine where the graph of the function $f(x)=\sin 9 x$ is concave upward and where it is concave downward on the interval $0 \leq x \leq \frac{2 \pi}{9}$ . Also, find all inflection points of the function.