Expanding:

`f(t)=t^2 · u(t)-t^2 · u(t-2) + 4 · u(t-2)`

`f(t)=t^2 · {u(t) - u(t-2)} + 4 · u(t-2)`

So our graph is as follows. It is a parabola before `t=2`, and then has constant value `4` thereafter.