Problem $3\mathrm{.}4.[3$ pts$]$ Let $\backslash ($ f$($x$)\backslash )$ be a sufficiently many times differentiable $($twice is enough$)$ single variable real valued function. Find the curvature of the graph of $\backslash ($ f $\backslash ),$ living in $\backslash ($ x y $\backslash )-$plane, as a formula just in terms of $\backslash ($ f $\backslash )$ and its higher derivatives.