Consider the following parametric curve.

$x=e^t-9t,y=12e^{\frac{t}{2}},0t3$

Set $upan$ integral that can $be$ used $to$ exact length $of$ the given curve.

$L={\displaystyle \underset{0}{\overset{\phantom{}}{}}}[\sqrt[\phantom{2}]{(e^t-9{)}^2+(12t{e}^{(\frac{t^2}{2})})2}]dt$

Find the exact length $of$ the curve.