How do I solve the integral x|x|dx?

  • Thread starter Telemachus
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In summary, the conversation involves solving the integral of x|x|dx and the suggested approach is to distinguish between the cases of x>=0 and x<0 and then proceed with the calculation. There is also a mention of Hurkyl not giving a straightforward answer, followed by a playful exchange about the Socratic method.
  • #1
Telemachus
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Homework Statement


I must solve [tex]\displaystyle\int_{}^{}x|x|dx[/tex]

How should I proceed?
 
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  • #2
I try starting with one of the first things you learned about solving problems involving |x|.
 
  • #3
You just distinguish the two cases x>=0 or x<0 and then teh calculation is straighforward. in the first case you wil have the integral of x*x and in the second you will have the integral of -x*x
 
  • #4
Quantumjump said:
You just distinguish the two cases x>=0 or x<0 and then teh calculation is straighforward. in the first case you wil have the integral of x*x and in the second you will have the integral of -x*x

I wonder why Hurkyl didn't just say that in his reply... hmm...
I guess he doesn't know how to do it... :eek:
 
  • #5
Thanks :P
 
  • #6
The Chaz said:
I wonder why Hurkyl didn't just say that in his reply... hmm...
I guess he doesn't know how to do it... :eek:
Are you serious?
 
  • #7
Unit said:
Are you serious?

Just guessing here, but I would say obviously no, he isn't serious. Rather it is a gentle jab at quantumjump for not giving the OP a chance to think for himself.
 
  • #8
LCKurtz said:
Just guessing here, but I would say obviously no, he isn't serious. Rather it is a gentle jab at quantumjump for not giving the OP a chance to think for himself.

It was either THAT, or I was totally slamming Hurkyl (but not both)!

I prefer the Socratic method to spoon-feeding.
 

1. How do I find the indefinite integral of x|x|dx?

The indefinite integral of x|x|dx is equal to (1/3)x^3 + (1/4)x^4 + C, where C is the constant of integration. This can be found by using the power rule for integration and substituting x|x| for u.

2. What is the process for solving the definite integral of x|x|dx?

The process for solving the definite integral of x|x|dx involves finding the indefinite integral first, then plugging in the upper and lower limits of integration and subtracting the results. This will give you the value of the definite integral.

3. Can I use substitution to solve x|x|dx?

Yes, substitution can be used to solve x|x|dx. You can substitute u = x|x| and then use the power rule for integration to find the indefinite integral.

4. Is there a shortcut method for solving x|x|dx?

No, there is no shortcut method for solving x|x|dx. The process of finding the indefinite integral and plugging in the limits of integration is the most efficient way to solve this integral.

5. Can I use integration by parts to solve x|x|dx?

Yes, you can use integration by parts to solve x|x|dx. However, it will involve multiple steps and may not be the most efficient method. It is recommended to use substitution or the power rule for integration instead.

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