Let [tex]\( f \)[/tex] be the piecewise defined function shown below:

[tex]\[
f(x)=\left\{\begin{array}{ll}
3x - 2, & x \leq 1 \\
x^2 + 1, & x \ \textgreater \ 1
\end{array}\right.
\][/tex]

Find the average rate of change of [tex]\( f \)[/tex] over the interval [tex]\([-2, 3]\)[/tex].



Answer :

To find the average rate of change of the function [tex]\( f \)[/tex] over the interval [tex]\([-2, 3]\)[/tex], we need to follow these steps:

1. Define the function [tex]\( f \)[/tex] at the specified points [tex]\( x_1 = -2 \)[/tex] and [tex]\( x_2 = 3 \)[/tex].

2. Evaluate the function at these points:
- For [tex]\( x_1 = -2 \)[/tex], since [tex]\(-2 \leq 1\)[/tex], we use the formula [tex]\( f(x) = 3x - 2 \)[/tex]:
[tex]\[ f(-2) = 3(-2) - 2 = -6 - 2 = -8 \][/tex]
- For [tex]\( x_2 = 3 \)[/tex], since [tex]\( 3 > 1 \)[/tex], we use the formula [tex]\( f(x) = x^2 + 1 \)[/tex]:
[tex]\[ f(3) = 3^2 + 1 = 9 + 1 = 10 \][/tex]

3. Find the average rate of change of [tex]\( f \)[/tex] over the interval [tex]\([x_1, x_2] = [-2, 3]\)[/tex] using the formula:
[tex]\[ \text{Average rate of change} = \frac{f(x_2) - f(x_1)}{x_2 - x_1} \][/tex]

4. Substitute the values we found into the formula:
- [tex]\( f(x_1) = f(-2) = -8 \)[/tex]
- [tex]\( f(x_2) = f(3) = 10 \)[/tex]
- [tex]\( x_1 = -2 \)[/tex]
- [tex]\( x_2 = 3 \)[/tex]

[tex]\[ \text{Average rate of change} = \frac{10 - (-8)}{3 - (-2)} = \frac{10 + 8}{3 + 2} = \frac{18}{5} = 3.6 \][/tex]

Summary of results:
- [tex]\( f(-2) = -8 \)[/tex]
- [tex]\( f(3) = 10 \)[/tex]
- Average rate of change = 3.6