Exercise 101

Using the Heaviside function $u(t)$, write down the function $$f(t) = \begin{cases} 0 & \text{if } \; \phantom{1 \leq {}} t < 1 , \\ t-1 & \text{if } \; 1 \leq t < 2 , \\ 1 & \text{if } \; 2 \leq t . \end{cases}$$