Given the graph of f(x), on which interval is the average rate of change the greatest?

Check the final answer first, then review the worked steps.

Problem

Given the graph of f(x), on which interval is the average rate of change the greatest?

Answer

3

Step-by-step solution

  1. Understand Average Rate of Change: The average rate of change of a function $f(x)$ over an interval $[a, b]$ is given by the formula $\frac{f(b) - f(a)}{b - a}$. This represents the slope of the secant line connecting the points $(a, f(a))$ and $(b, f(b))$ on the graph of the function.

2. Identify Points from the Graph: We need to find the coordinates of the points on the graph that correspond to the endpoints of the given intervals. From the graph, we can identify the following points:
- At $x=0$, $f(0) = -2$
- At $x=1$, $f(1) = 1$
- At $x=4$, $f(4) = -1$
- At $x=5$, $f(5) = -1$
- At $x=6$, $f(6) = 0$

3. Calculate Average Rate of Change for Each Interval: Now, we calculate the average rate of change for each of the given intervals:
- Interval [1, 4]: $a=1$, $b=4$. $f(1)=1$, $f(4)=-1$. Average rate of change = $\frac{f(4) - f(1)}{4 - 1} = \frac{-1 - 1}{3} = \frac{-2}{3}$.
- Interval [5, 6]: $a=5$, $b=6$. $f(5)=-1$, $f(6)=0$. Average rate of change = $\frac{f(6) - f(5)}{6 - 5} = \frac{0 - (-1)}{1} = \frac{1}{1} = 1$.
- Interval [0, 1]: $a=0$, $b=1$. $f(0)=-2$, $f(1)=1$. Average rate of change = $\frac{f(1) - f(0)}{1 - 0} = \frac{1 - (-2)}{1} = \frac{3}{1} = 3$.
- Interval [4, 5]: $a=4$, $b=5$. $f(4)=-1$, $f(5)=-1$. Average rate of change = $\frac{f(5) - f(4)}{5 - 4} = \frac{-1 - (-1)}{1} = \frac{0}{1} = 0$.

4. Compare the Average Rates of Change: We compare the calculated average rates of change:
- Interval [1, 4]: $-\frac{2}{3}$
- Interval [5, 6]: $1$
- Interval [0, 1]: $3$
- Interval [4, 5]: $0$

  1. Determine the Greatest Average Rate of Change: The greatest value among these is $3$, which corresponds to the interval $[0, 1]$.