Find the difference quotient [tex]\frac{f(x+h)-f(x)}{h}[/tex], where [tex]h \neq 0[/tex], for the function below.

[tex]\[ f(x) = \frac{1}{x+6} \][/tex]

Simplify your answer as much as possible.

[tex]\[ \frac{f(x+h)-f(x)}{h} = \boxed{\ } \][/tex]



Answer :

To find the difference quotient [tex]\(\frac{f(x+h) - f(x)}{h}\)[/tex] for the function [tex]\( f(x) = \frac{1}{x+6} \)[/tex], we will follow these steps:

1. Evaluate [tex]\( f(x + h) \)[/tex]:

Given [tex]\( f(x) = \frac{1}{x+6} \)[/tex], substitute [tex]\( x + h \)[/tex] into the function:
[tex]\[ f(x + h) = \frac{1}{(x + h) + 6} = \frac{1}{x + h + 6} \][/tex]

2. Form the difference quotient:

The difference quotient is given by:
[tex]\[ \frac{f(x + h) - f(x)}{h} \][/tex]

Substitute [tex]\( f(x + h) \)[/tex] and [tex]\( f(x) \)[/tex] into this expression:
[tex]\[ \frac{\frac{1}{x + h + 6} - \frac{1}{x + 6}}{h} \][/tex]

3. Combine the fractions in the numerator:

To combine the fractions, find a common denominator:
[tex]\[ \frac{1}{x + h + 6} - \frac{1}{x + 6} = \frac{(x + 6) - (x + h + 6)}{(x + h + 6)(x + 6)} \][/tex]

Simplify the numerator:
[tex]\[ (x + 6) - (x + h + 6) = x + 6 - x - h - 6 = -h \][/tex]

So, the numerator becomes:
[tex]\[ \frac{-h}{(x + h + 6)(x + 6)} \][/tex]

4. Divide by [tex]\( h \)[/tex]:

Now, include the division by [tex]\( h \)[/tex]:
[tex]\[ \frac{\frac{-h}{(x + h + 6)(x + 6)}}{h} = \frac{-h}{h \cdot (x + h + 6)(x + 6)} \][/tex]

5. Simplify the expression:

Notice that [tex]\( h \)[/tex] in the numerator and the denominator can be canceled:
[tex]\[ \frac{-h}{h \cdot (x + h + 6)(x + 6)} = \frac{-1}{(x + h + 6)(x + 6)} \][/tex]

Therefore, the simplified difference quotient is:
[tex]\[ \frac{f(x+h)-f(x)}{h} = \frac{-1}{(x+6)(x+h+6)} \][/tex]
This is the final simplified form.

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