Given the following system: $$\begin{align} u''_1(t)+u_1(t)+\frac{1}{3}u_2(t)&=0, \\ u''_2(t)-0.5u_1(t)+0.5u_2(t)&=2\sin(1.5t) \end{align}$$ with the initial conditions $u_1(0)=u_2(0)=0$ and $u_1'(0)=u_2'(0)=0$, determine the response at $t=5$ using 4th-order Runge-Kutta equation with step size $h=0.01$.
How do I set up the recursion equation for this?