$y(t) = -4e^{-5t} + 5e^{-4t}$, $t \ge 0$.
% Plotting the system response
t = [0:0.01:3]; % Create a vector of time instants
% Compute the response
y = 12*exp(-2*t)-12*exp(-3*t)+1;
% Graph the output signal
clf;
plot(t,y,'b-');
axis([0,3,-1,4]);
title('General response y(t)');
xlabel('t (sec)');
ylabel('Amplitude');
grid;