Integration using exponentials 2

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In summary: You're better off slowly reintroducing things one by one until you have a much better understanding of them.Thanks for your answers. In summary, the website suggests that if you are motivated to learn math and science, you should start with something simpler and work your way up to more complex problems.
  • #1
g.lemaitre
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Homework Statement




Screenshot2012-10-17at24825AM.png


For this forum they use the following integration:

Screenshot2012-10-17at24832AM.png




The Attempt at a Solution



Where does (u+a) come from? In step 2 why does the side on the left of the plus sign become zero? In step 3, how does A(0+a√π/λ) = a

This website likes you to work on problems but I can't work on something for which step 1 is a mystery.
 
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  • #2
g.lemaitre said:
Where does (u+a) come from?
They do a change of variables, x-a = u, so x= u+a

g.lemaitre said:
In step 2 why does the side on the left of the plus sign become zero?
The easiest way to see this is to notice that the integrand is an odd function (that is, f(-x) = -f(x)) and therefore the integral over an even interval [-n,n] is zero.

g.lemaitre said:
In step 3, how does A(0+a√π/λ) = a
Did they calculate the value for A before? What you are doing here is calculating an expectation value of a random variable, so it should be true that
[tex] \int_{-\infty}^\infty dx Ae^{-\lambda(x-a)^2} dx = 1 [/tex]

g.lemaitre said:
This website likes you to work on problems but I can't work on something for which step 1 is a mystery.
Yes but you can't explain every single operation you do. It just seems to me you're trying to do assignments which are a bit too difficult for you. Maybe start from something easier?
 
  • #3
Thanks for your answers.

Yes but you can't explain every single operation you do. It just seems to me you're trying to do assignments which are a bit too difficult for you. Maybe start from something easier?

Let's say my motivation to learn math and science right now (I'm into the humanities) on a scale of 1 to 10 is about 3. I don't have the motivation to go back and learn more calculus. I just want to see how much QM I can get through with the calc I have. Then after about 2 years hopefully I'll be able to make another effort to learn math and physics with a huge burst of motivation. This time around I dedicated about 1000 hours towards math and physics, after a two year break I'll put forth another 1000 hour effort if I have the time.
 
  • #4
g.lemaitre said:
Thanks for your answers.



Let's say my motivation to learn math and science right now (I'm into the humanities) on a scale of 1 to 10 is about 3. I don't have the motivation to go back and learn more calculus. I just want to see how much QM I can get through with the calc I have. Then after about 2 years hopefully I'll be able to make another effort to learn math and physics with a huge burst of motivation. This time around I dedicated about 1000 hours towards math and physics, after a two year break I'll put forth another 1000 hour effort if I have the time.

But it does not speed things up if you jump over things you haven't learned/have forgotten/whatever. In fact it's likely it's making your learning slower.
 

FAQ: Integration using exponentials 2

What is integration using exponentials 2?

Integration using exponentials 2 is a method of finding the integral of a function that involves an exponential term in the form of e^x or a^x, where a is a constant. It is an advanced technique in calculus that is used to solve complex integrals.

What are the steps involved in integration using exponentials 2?

The first step is to identify the function that needs to be integrated. Then, we use the power rule to integrate any terms without an exponent. Next, we use the substitution method to simplify the integral. Finally, we apply the integration by parts method to solve the integral.

When and why is integration using exponentials 2 used?

Integration using exponentials 2 is used when the traditional methods of integration, such as substitution or integration by parts, are not suitable for solving the integral. It is also used to solve integrals that involve exponential functions, which are commonly found in physics and engineering problems.

What are some common mistakes made in integration using exponentials 2?

One common mistake is forgetting to use the power rule to integrate terms without an exponent. Another mistake is not choosing the correct substitution to simplify the integral. It is also important to be careful with signs and constants when applying the integration by parts method.

Can integration using exponentials 2 be used for all types of integrals?

No, integration using exponentials 2 is not suitable for all types of integrals. It is mainly used for integrals that involve exponential functions or integrals that cannot be solved using traditional methods. For other types of integrals, different techniques may be more effective.

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