Question

consider the function

Answer 1

\(\left\{\begin{matrix}
0 &t<1 \\
t^2& 1 \leq t < 2 \\
t^2+2-2 & t>2
\end{matrix}\right.\)

Answer 2

how do express in unit step function?

Answer 3

I don't know but I think this is simple and will help you.
http://www.utdallas.edu/dept/abp/PDF_Files/DE_Folder/Unit_Step_Function.pdf

Answer 4

what is that third bit ? \(t^2+2-2\)?