---

tt=input('ввести временной интервал tn<=t<=tk [tn tk]:');

u0=@(t)t-1;
u1=@(t)(98-40*t-23*exp(-5*t))/75;
u2=@(t)2-t;

figure()
fplot(@(t)[u0(t) u1(t) u2(t)],tt)
grid on
legend('U0(t)','U1(t)','U2(t)')
xlabel('t')
ylabel('U(t)')