try this:
function dvdt = gprime(t,v)
global R
global C
V = 5*sin(30*2*pi*t) + 0.1*sin(5400*2*pi*t);
dvdt = (-1/(R*C))*v + (-1/(R*C))*V;
end
Then create another script like that, to resolve ODE.
clear all
clf
global R
global C
R = 1/(500*2*pi*1*10.^(-6));
C = 1*10.^(-6);
v0 = [0];
tspan = [0:0.001:2];
[t,x]=ode45(@gprime,tspan,v0);
plot(t,x)