AP Calculus AB : Antiderivatives by substitution of variables

Study concepts, example questions & explanations for AP Calculus AB

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Example Questions

Example Question #21 : Antiderivatives By Substitution Of Variables

Integrate:

Possible Answers:

Correct answer:

Explanation:

To integrate, the following substitution was made:

Now, we rewrite the integral in terms of u and integrate:

The following rule was used for integration:

Finally, rewrite the final answer in terms of our original x term:

Example Question #22 : Antiderivatives By Substitution Of Variables

Evaluate the integral

Possible Answers:

Correct answer:

Explanation:

We can make a u substitution in the following way:

, and therefore 

Simplifying the integral, we get

Rewriting in terms of x, we get

Example Question #21 : Antiderivatives By Substitution Of Variables

Solve:

 

Possible Answers:

Correct answer:

Explanation:

To integrate, we must make the following substitution:

Rewriting the integral in terms of u and integrating, we get

The following rule was used for integration:

Replacing u with our original x term, we get

Example Question #23 : Antiderivatives By Substitution Of Variables

Solve:

Possible Answers:

Correct answer:

Explanation:

To integrate, we must make the following substitution:

Rewriting the integral in terms of u and integrating, we get

The following rule was used for integration:

Replacing u with our original x term, we get

Example Question #71 : Techniques Of Antidifferentiation

Calculate:

Possible Answers:

Correct answer:

Explanation:

Rewrite the integrand as follows:

.

The integral can be rewritten as

Now, use -substitution, setting . It follows that 

The limits of integration can be rewritten as

The integral becomes

Integrate:

,

the correct response.

Example Question #73 : Techniques Of Antidifferentiation

Evaluate the following integral 

Possible Answers:

Correct answer:

Explanation:

The integral can be solved by using a variable substitution

Replacing  with , we get our final answer, which is

Example Question #231 : Integrals

Evaluate the following integral 

 

Possible Answers:

Correct answer:

Explanation:

We solve the problem by making a variable substitution

The integral then becomes

Substituting  for , we get our final answer

Example Question #25 : Antiderivatives By Substitution Of Variables

Solve:

Possible Answers:

Correct answer:

Explanation:

To integrate, it is easiest to break the integral into the sum of two integrals:

To integrate the first integral, we must make the following substitution:

The derivative was found using the rule itself.

Rewriting the first integral in terms of u and integrating, we get

which was found using the rule itself.

Replacing u with our original x term, we get

The second integral is equal to

and was found using the following rule:

Adding our two results, and combining the two constants of integration into a single integration constant, we get

 

Example Question #76 : Techniques Of Antidifferentiation

Calculate the integral in the following expression:

 

Possible Answers:

Correct answer:

Explanation:

The simplest path to follow when trying to integrate a lot of trig expressions is often to put everything in terms of sin(x) and cos(x). Doing this for the above expressions yields:

Next, we look for expressions that we know how to integrate, based on the following facts:

And, of course, the simpler derivatives of sin(x) and cos(x).

 

Looking for these above expressions in our integral, we note that 

Breaking this up into two integrals, we see that the second immediately can be simplified into -csc(x) + C. The first, while a bit more tricky, just requires you to realize that sec(x)tan(x) is the derivative of sec(x). Thus, if you use a substitution of variables (u-sub) with u = sec(x), you will get,

and

In this form, it is clear to see that the integral is just   where u = sec(x)

 

Combining our two integrals, we get a final answer of 

Example Question #77 : Techniques Of Antidifferentiation

Evaluate the integral

Possible Answers:

Correct answer:

Explanation:

To evaluate the integral, we make a variable substitution for 

The integral then becomes

Substituting  back in for , the final answer is

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