Integrating by Substitution: Solving Integrals with Square Roots

In summary, "Integration by Substitution" is a method used in calculus to simplify integrals by substituting a variable in the integrand with another variable or expression. It is used when the integrand contains a function that can be simplified by substitution, especially when it involves a composite function. To perform this method, one must identify the function to be substituted, choose an appropriate substitution, rewrite the integrand, and solve the new integral. The purpose of "Integration by Substitution" is to simplify and evaluate integrals that cannot be solved using other methods. Some common mistakes to avoid are choosing an inappropriate substitution, forgetting to substitute back in the original variable, misinterpreting the chain rule, making algebraic errors, and not checking the
  • #1
futb0l
32
0
Can anyone help me with the following integrals (integrate by substitution)?

[tex]
\int{\frac{dx}{\sqrt{x^2 - 4}}}
[/tex]

[tex]
\int{\frac{dx}{\sqrt{x^2 + 4}}}
[/tex]

I have no idea whatsoever on how to do it.
 
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  • #2
[tex] \int{\frac{dx}{\sqrt{x^2 - 4}}} [/tex]. Use the substitution [tex] x = 2\sec \theta [/tex]

[tex]
\int{\frac{dx}{\sqrt{x^2 + 4}}}
[/tex] Use the substitution [tex] x = 2\tan \theta [/tex]
 
  • #3
Right, thanks a lot :D
 

FAQ: Integrating by Substitution: Solving Integrals with Square Roots

What is "Integration by Substitution"?

"Integration by Substitution" is a method used in calculus to evaluate integrals. It involves substituting a variable in the integrand with another variable or expression in order to simplify the integral and make it easier to solve.

When is "Integration by Substitution" used?

"Integration by Substitution" is used when the integrand contains a function that can be simplified by using a substitution. This method is especially useful when the integrand contains a composite function, where one function is nested inside another.

How do you perform "Integration by Substitution"?

To perform "Integration by Substitution", follow these steps:
1. Identify the function that can be substituted in the integrand.
2. Choose an appropriate substitution, usually denoted by u.
3. Rewrite the integrand in terms of u.
4. Find the derivative of u and substitute it in the integral.
5. Solve the new integral.
6. Substitute back in the original variable to get the final answer.

What is the purpose of "Integration by Substitution"?

The purpose of "Integration by Substitution" is to simplify an integral and make it easier to solve. It can also be used to evaluate integrals that cannot be solved using other methods.

What are some common mistakes to avoid when using "Integration by Substitution"?

Some common mistakes to avoid when using "Integration by Substitution" include:
- Choosing an inappropriate substitution
- Forgetting to substitute back in the original variable
- Misinterpreting the chain rule and not properly substituting the derivative
- Making algebraic errors when simplifying the integral
- Not checking the final answer using differentiation

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