Solve the given problems related to the indicated examples of this section.

In Example 5, find f(2) and f(5).

Data from Example 5

In a certain electric circuit, the current i (in mA) is a function of the time t (in s), which means i = f (t). The function is

Because negative values of t are not usually meaningful, f(t) is not defined for t < 0. Find the current for t = 3 s, t = 6 s, and t = −1 s. We are to find f(3), f(6), and f (−1), and we see that values of this function are determined differently depending on the value of t. Because 3 is between 0 and 4,

f(3) = 8 − 2(3) = 2 or i = 2mA

Because 6 is greater than 4, f (6) = 0, or i = 0 mA. We see that i = 0 mA for all values of t that are 4 or greater. Because f(t) is not defined for t < 0, f (−1) is not defined.

Transcribed Image Text:

f(t) = 8 0 2t (for 0 t ≤ 4s) (fort > 4s)