Calculating the Average Value of a Function Between Two Limits

In summary, the average value of the function 1/x between x=2/3 and x=8/3 is ln2. This is calculated using the formula 1/(b-a) ∫f(x) dx and plugging in the values for a, b, and the function 1/x. The final step is to take the natural logarithm of the resulting expression, which simplifies to ln2.
  • #1
Justabeginner
309
1

Homework Statement


What is the average value of a function 1/x between x=2/3 and x=8/3?


Homework Equations


1/(b-a) ∫f(x) dx with a and b being the lower and upper limits, respectively


The Attempt at a Solution



1/([8/3] - [2/3])∫1/x dx
1/(6/3) ∫1/x dx
1/2 ∫1/x dx
1/2 * (ln x)

Plug in:
(ln {8/3})/2 - (ln {2/3}/2)
ln 4/2
ln 2

Is this correct? Thanks :)
 
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  • #2
Justabeginner said:

Homework Statement


What is the average value of a function 1/x between x=2/3 and x=8/3?


Homework Equations


1/(b-a) ∫f(x) dx with a and b being the lower and upper limits, respectively


The Attempt at a Solution



1/([8/3] - [2/3])∫1/x dx
1/(6/3) ∫1/x dx
1/2 ∫1/x dx
1/2 * (ln x)

Plug in:
(ln {8/3})/2 - (ln {2/3}/2)
ln 4/2
ln 2

Is this correct? Thanks :)
Looks good.

Though, just to be clear, your reasoning for your last few steps was ##\frac{1}{2}\ln\left(\frac{(\frac{8}{3})}{(\frac{2}{3})}\right) = \frac{1}{2}\ln(4) = \ln(4^{\frac{1}{2}}) = \ln2##, correct?
 
  • #3
Yes, that is exactly what I have written on my paper here. Thank you so much for your help :)
 

Related to Calculating the Average Value of a Function Between Two Limits

What is the average value of a function?

The average value of a function is the average height of the graph of the function over a given interval. It represents the average output of the function over that interval.

How is the average value of a function calculated?

The average value of a function is calculated by finding the definite integral of the function over the given interval, and then dividing by the length of the interval.

Why is the average value of a function important?

The average value of a function is important because it can be used to find the total output or area under a curve, which has many practical applications in fields such as physics, economics, and engineering.

Can the average value of a function be negative?

Yes, the average value of a function can be negative if the function has negative values over the given interval. This means that on average, the function outputs negative values over that interval.

What is the relationship between the average value of a function and its maximum and minimum values?

The average value of a function lies between its maximum and minimum values. If the function is continuous, the average value will be equal to the function's output at some point between the maximum and minimum values.

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