$\left\{\begin{array}{l}\frac{d y}{d x}=y \\ V(0)=3\end{array}\right.$

Step 1 ：Given the first-order differential equation and initial condition: \(\left\{\begin{array}{l}\frac{d y}{d x}=y \\ V(0)=3\end{array}\right.\)

Step 2 ：Find the general solution to the differential equation: \(y(x) = C_1 e^x\)

Step 3 ：Apply the initial condition V(0) = 3: \(y(0) = C_1 e^0\)

Step 4 ：Solve for \(C_1\): \(C_1 = 3\)

Step 5 ：Substitute \(C_1\) back into the general solution: \(\boxed{y(x) = 3e^x}\)