Analyze the graph of the function $j(x)$ to find the $x$-value in the interval $\left(0,7\right)$ at which $j$ is not differentiable.

If a function $k$ has a derivative at the point $c$, what can be said about the continuity of $k$ at $c$?

Determine whether the given statement is true or false.

If a function $k$ is continuous at $d$, then $k$ must be differentiable at $d$?