Problem with math integral substitution

In summary, substitution is a technique used in math integrals to replace a variable with a new variable, making the integral easier to solve. The appropriate substitution should involve a function with a derivative present elsewhere in the integral and should simplify the integral. While substitution can be used for many integrals, some may require other techniques. Common mistakes when using substitution include missing substitutions and choosing an inappropriate substitution. Tips for effectively using substitution include practice, checking the answer, and being patient and persistent.
  • #1
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[tex]\int \frac{1}{4x+7*sqrt(x)}[/tex]

what would be a good u substituion for this problem? i can't think of any at the moment
 
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  • #2
[tex]y=\sqrt x[/tex] is a good start.
 
  • #3
The answer is [tex] \frac{1}{2}\ln (4\sqrt{x}+7) +C [/tex]

Daniel.

P.S.Sure,the integral is evaluated in [itex] (0,+\infty) [/itex].
 

FAQ: Problem with math integral substitution

What is the purpose of substitution in math integrals?

Substitution in math integrals is used to simplify complex integrals by replacing a variable with a new variable. This allows for the use of more familiar integration techniques and makes the integral easier to solve.

How do I choose the appropriate substitution for a math integral?

The most common approach is to look for a function within the integral that can be replaced with a new variable. This function should have a derivative that is present elsewhere in the integral. Additionally, the substitution should make the integral simpler and easier to solve.

Can substitution be used for all types of math integrals?

Yes, substitution is a commonly used technique for solving a variety of math integrals. However, there may be some integrals that cannot be solved solely through substitution and may require the use of other integration techniques.

What are some common mistakes when using substitution in math integrals?

One common mistake is not properly substituting for all instances of the original variable in the integral. It is important to carefully check for any missed substitutions before proceeding with the solution. Another mistake is choosing an inappropriate substitution, which can make the integral more complicated instead of simplifying it.

Are there any tips for effectively using substitution in math integrals?

It is helpful to practice with a variety of integrals to become familiar with when and how to use substitution. It can also be useful to check the answer by differentiating the solution back to the original integral. Additionally, it is important to be patient and persistent when using substitution, as it may take some trial and error to find the most suitable substitution for a given integral.

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