Integral Question (Riemann Sums)

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SUMMARY

The discussion focuses on Riemann sums and their application in approximating Riemann integrals as part of a final exam from the MIT Open Course Ware site for Single Variable Calculus. The general formula for the Riemann sum is established as Σ (f(k/n)/n) for k=1 to n, where the function is evaluated at the right endpoints of the subintervals. The participants also explore finding a Riemann integrable function f(x) on the interval [0, 1] that corresponds to the sum Σ (k/(k²+n²)), ultimately leading to the function f(k/n) = k/(k²+n²).

PREREQUISITES
  • Understanding of Riemann sums and integrals
  • Familiarity with Single Variable Calculus concepts
  • Ability to manipulate algebraic expressions
  • Knowledge of limits and continuity in functions
NEXT STEPS
  • Study the properties of Riemann integrable functions
  • Learn about the Fundamental Theorem of Calculus
  • Explore advanced topics in integration techniques
  • Investigate the convergence of Riemann sums
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Students of calculus, educators teaching Single Variable Calculus, and anyone looking to deepen their understanding of Riemann sums and integrals.

altcmdesc
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This is from a final exam on the MIT Open Course Ware site for Single Variable Calculus

Homework Statement



(a)(5 points) Write down the general formula for the Riemann sum approximating the Riemann integral,

1
\int f(x)dx
0

for the partition of [0,1] into n subintervals of equal length. Evaluate the function at the right endpoints of the subintervals.

(b)(5 points) Find a Riemann integrable function f(x) on the interval [0, 1] such that the formula for the Riemann sum from (a) equals the following formula,

n
\sum \frac{k}{k^{2}+n^{2}}
k=1

Show all work.


The Attempt at a Solution



I've figured out a) to be:

n
\sum \frac{f(k/n)}{n}
k=1

Using this result, on b) I get as far as:

f(k/n)=\frac{kn}{k^{2}+n^{2}}

But I can't get any farther.
 
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Divide the numerator and denominator by n^2. I.e. try to write the expression using only k/n.
 
Ah, I get it. x/(x2-1). Thanks
 
altcmdesc said:
Ah, I get it. x/(x2-1). Thanks

Um, x/(x^2+1), right? You're welcome.
 

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