The given pair of functions is
[tex]u_{1}(t) =e^{2t}, \, u_{2}(t)=e^{- \frac{3t}{2}} [/tex]
The derivatives are
[tex]u_{1}{'}=2e^{2t} \\ u_{2}^{'} = - \frac{3}{2} e^{- \frac{3t}{2} }[/tex]
The Wronskian is
[tex]W=\begin{pmatrix} e^{2t} & e^{- \frac{3t}{2}}\\2e^{2t} & - \frac{3}{2}e^{- \frac{3t}{2}} \end{pmatrix}=- \frac{3}{2}e^{t/2}-2e^{t/2}=- \frac{7}{2}e^{t/2} [/tex]
Answer: [tex]- \frac{7}{2}e^{ \frac{t}{2}} [/tex]