Integral: Evaluate x^3 sin (t^2) dt

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Homework Help Overview

The problem involves evaluating the integral of sin(t^2) with variable limits of integration, specifically from x to x^3. The context is within the subject area of calculus, particularly focusing on the application of the fundamental theorem of calculus.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of the fundamental theorem of calculus and whether the problem requires evaluating the integral or finding its derivative. Some express uncertainty about the integral's complexity and the relevance of Fresnel integrals.

Discussion Status

The discussion is ongoing, with various interpretations being explored regarding the nature of the problem. Some participants suggest using the fundamental theorem of calculus, while others question the original problem's wording and intent.

Contextual Notes

There is uncertainty about the exact requirements of the problem, with some participants questioning whether the integral should be evaluated directly or if the derivative is being sought. Additionally, there are concerns about the complexity of integrating sin(t^2) by hand.

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Homework Statement



Evaluate the integral (upper limit x^3 and lower limit x) sin (t^2) dt

Homework Equations





The Attempt at a Solution



I tried using the second fundamental theorem to do: 3x^2 sin (x^6) - sin (x^2). I'm not sure if this is right though.
 
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Is it some kind of a double integral?
 
what do you mean by double integral?
 
You have to use Fresnel integrals. Integrating the sin(t^2) by hand is not easy. What class is this for?
 
It's AP Calculus AB.
 
That question shouldn't be there, are you sure you read the problem right? could it have been (sin(t))^2 instead?The answer to the problem posted is as follows:

sqrt(Pi/2)[(S(sqrt(2/Pi)*x^3)-S(sqrt(2/Pi)*x)], where S(x) is the Fresnel integral of sin(t^2)dt from 0 to x.
 
I think they want the derivative not to evaluate the actual integral. Can I use the second fundamental theorem then?
 
Would you type in the instructions for the problem? I am not entirely sure what they are asking.
 
Frostbytez said:
I think they want the derivative not to evaluate the actual integral. Can I use the second fundamental theorem then?

The question does ask for the derivative of that integral, yes? And yes, you can use a fundamental theorem. And yes, you did it correctly.
 
  • #10
Frostbytez said:

Homework Statement



Evaluate the integral (upper limit x^3 and lower limit x) sin (t^2) dt

Homework Equations





The Attempt at a Solution



I tried using the second fundamental theorem to do: 3x^2 sin (x^6) - sin (x^2). I'm not sure if this is right though.

====

Yeah, I think that you are just over-complicating this... what is the derivative of
y = (-1/(t^2))cos(t^2) ...

Okay, the derviative of that is the integrand of your problem.
evalulating y from the top and bottom (of the integral domain) yields:
(-1/x^6)cos(x^6) +(1/x^2)cos(x^2)
 
  • #11
brydustin said:
====

Yeah, I think that you are just over-complicating this... what is the derivative of
y = (-1/(t^2))cos(t^2) ...

Okay, the derviative of that is the integrand of your problem.
evalulating y from the top and bottom (of the integral domain) yields:
(-1/x^6)cos(x^6) +(1/x^2)cos(x^2)

Wrong. The derivative of that is DEFINITELY not sin(t^2).
 

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