Ex $2$: ${\displaystyle \underset{c}{\overset{\phantom{}}{}}}f(x,y)d$s$,$ where $f(x,y)=\frac{x^3}{y}{?}_{0}x{2}^{lambd{a}_x^{f}y}=\frac{x^2}{2}$

$\{\begin{array}{ccc}\text{:}\text{v}\text{e}\text{c}& (r)(t)=(t,\frac{t^2}{2})\text{;}\text{v}\text{e}\text{c}(V)(t)=(l,& t)\text{;}\\ |vec(v)(t)|=\sqrt[\phantom{2}]{1+t^2}\end{array}$

$\{\begin{array}{ccc}\text{:}& \text{w}\text{i}\text{t}\text{l}\text{i}\text{n}& 3\%\end{array}$