Calculus 2 : Solving Integrals by Substitution

Study concepts, example questions & explanations for Calculus 2

varsity tutors app store varsity tutors android store

Example Questions

Example Question #41 : Solving Integrals By Substitution

Solve the indefinite integral using trigonemtric substitution

Possible Answers:

Correct answer:

Explanation:

We substitute 

to solve the integral. Solving for dx,

Substituting these values into the integral yields

Solving for  from

gives us

And so the indefinite integral is

Example Question #41 : Solving Integrals By Substitution

Evaluate the following indefinite integral:

Possible Answers:

Correct answer:

Explanation:

The integrand is composed of a function as well as its derivative multiplied by a constant. Hence, we can find the antiderivative via u-substitution as follows:

Let . Then , and so . Thus,

 

                                  

                                  

Example Question #42 : Solving Integrals By Substitution

Evaluate the following indefinite integral:

Possible Answers:

Correct answer:

Explanation:

The integrand can be evaluated by means of the u-substitution method, as follows:

Let . Then , and so

Example Question #43 : Solving Integrals By Substitution

Evaluate the following indefinite integral:

Possible Answers:

Correct answer:

Explanation:

Here, an understanding of trigonometric identities, as well as the appropriate selection of a dummy variable for u-substitution, is required. To figure out which function to represent "u" (cosine or sine), simply re-write the integrand as

                                

Remembering that ,

Now, we can substitute  to yield

 

because if , then , which implies .

At this point, all that is left to do is expand the polynomial and evaluate the integrand:

                               

                                

Example Question #625 : Finding Integrals

Find the value of

.

Possible Answers:

Correct answer:

Explanation:

To perform this integration, we use a substitution.

Since the derivative of is , we choose our substitution to be .

Differentiating gives us,

 .

Now we can substitute this into our integral. We will have,

 .

Along with this substitution, we must also change our limits of and . To do so, we take these values and plug them in for  in the formula .

Doing so, we obtain and .

Now our integral will be transformed as follows,

 .

This integral is now easy to integrate, for the function integrates to .

Thus we have,

 .

Therefore, the answer to the integral is,

.

Example Question #46 : Solving Integrals By Substitution

Evaluate the following integral:

Possible Answers:

Correct answer:

Explanation:

To integrate, we must first make the following substitution:

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

The integral was performed using the following rule:

Note that the rule contains a fraction in front of the inverse trig function. Do not confuse this fraction with the fraction coming from the u substitution!

Finally, replace u with our original term and multiply the constants:

Example Question #631 : Finding Integrals

Evaluate the following integral:

Possible Answers:

Correct answer:

Explanation:

To evaluate the integral, we can first use the fact that cosine and secant are inverses of each other, so they cancel:

Now, we must make the following substitution:

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

We used the following rule to integrate:

Finally, replace u with our original x term:

Example Question #48 : Solving Integrals By Substitution

Possible Answers:

Correct answer:

Explanation:

To integrate this problem, you have to use "u" substitution. Assign . Then, find du, which is 2x. That works out since we can then replace the other x in the original problem. We will have to offset the 2 though: . Now plug in all the parts: . Now, integrate as normal, remembering to raise the exponent by 1 and then also putting that result on the bottom: . Simplify, add a C because it is an indefinite integral, and substitute your original expression back in: .

Example Question #41 : Solving Integrals By Substitution

Possible Answers:

Correct answer:

Explanation:

To integrate this problem, use "u" substitution. Assign , . Substitute everything in so you can integrate: . Recall that when there is a single variable on the denominator, the integral is ln of that term. Therefore, after integrating, you get . Sub back in your original expression and add C because it is an indefinite integral: .

Example Question #50 : Solving Integrals By Substitution

Evaluate the following integral using the substitution method:

Possible Answers:

Correct answer:

Explanation:

Make the substitution:

Learning Tools by Varsity Tutors