Finding an Integral from an Unknown Function

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SUMMARY

The discussion focuses on solving the integral equation \( x \sin(\pi x) = \int_0^{x^2} f(t) dt \) to find \( f(4) \). Participants confirm the application of the Fundamental Theorem of Calculus and emphasize the need to use the chain rule due to the upper limit being \( x^2 \). The derivative of the left-hand side, \( x \sin(\pi x) \), must be equated to the derivative of the integral on the right-hand side, leading to the conclusion that \( f(x^2)(2x) = \frac{d}{dx}(x \sin(\pi x)) \).

PREREQUISITES
  • Understanding of the Fundamental Theorem of Calculus
  • Knowledge of the chain rule in differentiation
  • Familiarity with derivatives of trigonometric functions
  • Basic concepts of integral calculus
NEXT STEPS
  • Study the Fundamental Theorem of Calculus in detail
  • Learn about the chain rule and its applications in calculus
  • Practice differentiating trigonometric functions, specifically \( \sin(\pi x) \)
  • Explore examples of integrals with variable upper limits
USEFUL FOR

Students and educators in calculus, particularly those focusing on integral and differential calculus, as well as anyone seeking to deepen their understanding of the Fundamental Theorem of Calculus and its applications.

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Homework Statement


If xsin[tex]\pi[/tex]x = [tex]\int[/tex]f(t) dt, where is a continuous function, find f(4).
b=x2, a=0

Homework Equations





The Attempt at a Solution


I assumed that the problem dealt with the Fundamental Theroem of Calculus so I began by saying that g(x)=xsin[tex]\pi[/tex]x but that is as far as it makes sense to me. Could anyone confirm to me that I am following the correct path?
 
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Yes, if
[tex]x sin(\pi x)= \int_0^{x^2} f(t)dt[/quote]<br /> you can apply the Fundamental theorem but if you do that, because the upper limit is "x<sup>2</sup>" rather than "x", you need to use the chain rule also:<br /> [tex]F(x)= \int_0^x^2 f(t)dt= \int_0^u f(t)dt[/tex]<br /> where u= x<sup>2</sup>. The derivative of the right hand side is F'(u)(du/dx)= f(u)(2x)= f(x<sup>2</sup>)(2x). That is equal to the derivative of the left hand side. What is the derivative of [itex]x sin(\pi x)[/itex]?<br /> [tex]f([/tex][/tex]
 

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