Connect with experts and get insightful answers on IDNLearn.com. Receive prompt and accurate responses to your questions from our community of knowledgeable professionals ready to assist you at any time.

Ex 1: Consider the function given by [tex]f(x)=9-x^2[/tex]. Find its average rate of change between the following points. Carefully show the work that leads to your final answer.

(a) [tex]x=0[/tex] to [tex]x=3[/tex]

(b) [tex]x=-1[/tex] to [tex]x=5[/tex]


Sagot :

To find the average rate of change of the function [tex]\( f(x) = 9 - x^2 \)[/tex] over given intervals, we will use the formula for the average rate of change, which is:

[tex]\[ \text{Average Rate of Change} = \frac{f(x_2) - f(x_1)}{x_2 - x_1} \][/tex]

Let's apply this to each set of points provided:

### (a) For the interval [tex]\( x = 0 \)[/tex] to [tex]\( x = 3 \)[/tex]:

1. Calculate [tex]\( f(x) \)[/tex] at the given points:
- At [tex]\( x_1 = 0 \)[/tex]:
[tex]\[ f(0) = 9 - 0^2 = 9 \][/tex]
- At [tex]\( x_2 = 3 \)[/tex]:
[tex]\[ f(3) = 9 - 3^2 = 9 - 9 = 0 \][/tex]

2. Calculate the change in [tex]\( f(x) \)[/tex] and [tex]\( x \)[/tex]:
- Change in [tex]\( f(x) \)[/tex]:
[tex]\[ \Delta f = f(3) - f(0) = 0 - 9 = -9 \][/tex]
- Change in [tex]\( x \)[/tex]:
[tex]\[ \Delta x = 3 - 0 = 3 \][/tex]

3. Compute the average rate of change:
[tex]\[ \text{Average Rate of Change} = \frac{\Delta f}{\Delta x} = \frac{-9}{3} = -3.0 \][/tex]

So, the average rate of change from [tex]\( x = 0 \)[/tex] to [tex]\( x = 3 \)[/tex] is -3.0.

### (b) For the interval [tex]\( x = -1 \)[/tex] to [tex]\( x = 5 \)[/tex]:

1. Calculate [tex]\( f(x) \)[/tex] at the given points:
- At [tex]\( x_1 = -1 \)[/tex]:
[tex]\[ f(-1) = 9 - (-1)^2 = 9 - 1 = 8 \][/tex]
- At [tex]\( x_2 = 5 \)[/tex]:
[tex]\[ f(5) = 9 - 5^2 = 9 - 25 = -16 \][/tex]

2. Calculate the change in [tex]\( f(x) \)[/tex] and [tex]\( x \)[/tex]:
- Change in [tex]\( f(x) \)[/tex]:
[tex]\[ \Delta f = f(5) - f(-1) = -16 - 8 = -24 \][/tex]
- Change in [tex]\( x \)[/tex]:
[tex]\[ \Delta x = 5 - (-1) = 5 + 1 = 6 \][/tex]

3. Compute the average rate of change:
[tex]\[ \text{Average Rate of Change} = \frac{\Delta f}{\Delta x} = \frac{-24}{6} = -4.0 \][/tex]

So, the average rate of change from [tex]\( x = -1 \)[/tex] to [tex]\( x = 5 \)[/tex] is -4.0.

### Summary:

- The average rate of change from [tex]\( x = 0 \)[/tex] to [tex]\( x = 3 \)[/tex] is [tex]\(-3.0\)[/tex].
- The average rate of change from [tex]\( x = -1 \)[/tex] to [tex]\( x = 5 \)[/tex] is [tex]\(-4.0\)[/tex].