Find Integral of sqrt(e^(9x)) - Incorrect Solution Explained

  • Thread starter 7yler
  • Start date
  • Tags
    Integral
In summary, the incorrect solution to finding the integral of sqrt(e^(9x)) is to simply take the square root of e^(9x) and integrate it, resulting in an answer of 1/18 * e^(9x/2) + C. This solution is incorrect because it does not take into account the chain rule and requires substitution and integration by parts. The correct solution involves substituting u = e^(9x) and du = 9e^(9x)dx, using integration by parts, and remembering to add the constant of integration (C) at the end. To avoid making mistakes when finding integrals, it is important to remember the rules of integration and to double check your work. Practice and familiarity
  • #1
7yler
31
0
Find the integral.
[tex]\int\sqrt{e^{9x}} dx[/tex]

I figured that [tex]\int\sqrt{e^{9x}} dx[/tex] is equal to [tex]\int(e^{9x/2}) dx[/tex] so the integral should simply be [tex]e^{9x/2}+C[/tex]

Why isn't this correct?
 
Physics news on Phys.org
  • #2
Take the derivative of your answer and you'll see what you left out. Almost got it.
 
  • #3
2/9! Thanks a ton.
 

1. What is the incorrect solution to finding the integral of sqrt(e^(9x))?

The incorrect solution is to simply take the square root of e^(9x) and integrate it, resulting in an answer of 1/18 * e^(9x/2) + C.

2. Why is this solution incorrect?

This solution does not take into account the chain rule, which is necessary when integrating exponential functions. The correct solution requires substitution and integration by parts.

3. Can you explain the correct solution in simpler terms?

The correct solution involves substituting u = e^(9x) and du = 9e^(9x)dx, which allows us to rewrite the integral as ∫sqrt(u)/9 du. We can then use integration by parts to solve for the integral and substitute back in u to get the final answer.

4. Are there any other common mistakes when finding integrals of exponential functions?

Yes, another common mistake is forgetting to add the constant of integration (C) at the end of the solution. This constant is necessary because when we take the derivative of a constant, it is equal to 0.

5. How can I avoid making these mistakes when finding integrals?

It is important to remember the rules of integration, such as the chain rule and integration by parts, and to always double check your work to make sure you have not made any errors. Practice and familiarity with these rules will also help to avoid making mistakes in the future.

Similar threads

  • Calculus and Beyond Homework Help
Replies
5
Views
1K
  • Calculus and Beyond Homework Help
Replies
5
Views
800
  • Calculus and Beyond Homework Help
Replies
22
Views
1K
  • Calculus and Beyond Homework Help
Replies
7
Views
710
  • Calculus and Beyond Homework Help
Replies
8
Views
764
  • Calculus and Beyond Homework Help
Replies
3
Views
2K
  • Calculus and Beyond Homework Help
Replies
7
Views
936
  • Calculus and Beyond Homework Help
Replies
14
Views
256
  • Calculus and Beyond Homework Help
Replies
9
Views
727
  • Calculus and Beyond Homework Help
Replies
4
Views
847
Back
Top