Given the function [tex]\( f(x) = \sqrt{x+3} - 2 \)[/tex], calculate the average rate of change between [tex]\( x = 6 \)[/tex] and [tex]\( x = 13 \)[/tex].

A. [tex]\(\frac{1}{7}\)[/tex]
B. [tex]\(-\frac{1}{7}\)[/tex]
C. 7
D. -7



Answer :

To solve this problem, let's break it down into a few steps.

1. Understanding the function:
Given the function [tex]\( f(x) = \sqrt{x + 3} - 2 \)[/tex].

2. Calculate the values of the function at the given points:
- For [tex]\( x = 6 \)[/tex]:
[tex]\[ f(6) = \sqrt{6 + 3} - 2 = \sqrt{9} - 2 = 3 - 2 = 1 \][/tex]
- For [tex]\( x = 13 \)[/tex]:
[tex]\[ f(13) = \sqrt{13 + 3} - 2 = \sqrt{16} - 2 = 4 - 2 = 2 \][/tex]

3. Plug in the function values into the average rate of change formula:
The average rate of change of a function [tex]\( f(x) \)[/tex] between [tex]\( x = a \)[/tex] and [tex]\( x = b \)[/tex] is given by:
[tex]\[ \text{Average rate of change} = \frac{f(b) - f(a)}{b - a} \][/tex]
Here, [tex]\( a = 6 \)[/tex] and [tex]\( b = 13 \)[/tex].

Substitute [tex]\( f(6) = 1 \)[/tex] and [tex]\( f(13) = 2 \)[/tex] into the formula:
[tex]\[ \text{Average rate of change} = \frac{f(13) - f(6)}{13 - 6} = \frac{2 - 1}{13 - 6} = \frac{1}{7} \][/tex]

4. Match the result with the given options:

The average rate of change is [tex]\(\frac{1}{7}\)[/tex], which matches choice:
[tex]\[ \frac{1}{7} \][/tex]

Thus, the answer is:
[tex]\[ \boxed{\frac{1}{7}} \][/tex]