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Example Questions
Example Question #14 : Average Values And Lengths Of Functions
Let f(x) bet a function continuous on the defined below and having the derivative
Find the length L of the graph of f(x) on the interval
To find the length of a line along a given function f(x) from a to b, utilize the equation
Applying the equation for this problem and using the given expression for f'(x):
Example Question #151 : Integral Applications
Find the average value of the function over the interval .
None of the other answers
None of the other answers
The correct answer is .
To find the average value of the function, we use
Average value ,
with in this case.
So we have
Using integration by parts with and hence , we have
Example Question #16 : Average Values And Lengths Of Functions
Find the arc length of the graph on the interval .
The arc length for a function on the interval is given by the following integral:
.
Thus we must compute the value of for the function .
To do so, we use the chain rule:
.
Now plugging to the arc length formula, and using the interval , we obtain,
.
Using the trig identity , our integral becomes:
.
In the last step above, we invoked the property
.
Since the expression in the absolute value is positive, we can get rid of the absolute value brackets.
Thus we obtain
.
Example Question #11 : Average Values And Lengths Of Functions
What is the average value of on the interval ?
To find the average value of a function, you must use the following equation:
. Now, we simply substitute our values, and integrate.
. Now, we plug in our bounds (upper - lower).
Example Question #151 : Integral Applications
Find the average value of the function from to .
The average value equation is
Now, all we have to do is plug in our limits.
The second term drops out because the natural log of equals zero. In the first term, natural log and cancel each other out, just leaving the out front.
Example Question #161 : Integral Applications
Determine the average value of the function
On the interval
The average value of a function on the interval is defined as
As such, we solve the expression
As such, the average value is
Example Question #20 : Average Values And Lengths Of Functions
Determine the average value of the function
On the interval
The average value of a function on the interval is defined as
As such, we solve the expression
As such, the average value is
Example Question #21 : Average Values And Lengths Of Functions
You will need a calculator for this question.
Find the surface area of revolution formed by the function, , from x=0 to x=2, when revolved around the y axis. Round to the nearest hundredth.
To find the surface area of a revolution, we must use the following formula.
, where "r" is the variable radius of the curve from the axis of revolution, and "ds" is the differential of the arc length of the curve at that radius. For this problem, "r" is simply the variable "x", because every point's radius from the axis of revolution (the y axis), is its x coordinate.
You can think of "ds" as the arc length formula after it is differentiated. Arc length is an integral, so the derivative of an integral is just what's inside that integral. Here that means .
"a" and "b" will be the x=0 and x=2 part of the question.
From this information we can rewrite the surface area formula as
Now we will find f'(x).
Plug in to the formula.
Now simplify .
Notice that the is part of the derivative of what is under the radical. This almost follows the basic integral form ,with , and . Let's force it to match the form exactly. First I will rewrite the square root as an exponent.
Now multiply by a form of 1 (highlighted in red) to force the "du" part of the integration form.
It may help to rewrite the expression in terms of to make it easier to apply integration rules. We just need to remember to convert back to x after integrating, before we plug in the bounds.
Now integrate.
Now convert u back to x. Recall that
Now plug in the upper and lower bounds.
Now use a calculator to find the approximate answer of
Example Question #21 : Average Values And Lengths Of Functions
Evaluate the average value of the function on the interval .
To solve for the average value on the interval we follow the following formula
For this problem we evaluate
Example Question #22 : Average Values And Lengths Of Functions
Evaluate the average value of the function on the interval .
To solve for the average value on the interval we follow the following formula
For this problem we evaluate
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