What Definite Integral Does This Riemann Sum Represent?

aselin0331
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Homework Statement



Rn=\sum(i*e^(-2i/n))/n^2, i=1

Identify this Riemann sum corresponding to a certain definite integral.

Homework Equations





The Attempt at a Solution



I got till 1/n^2 [1/e^(2/n)+2/e^(4/n)+3/e^(6/n)...n/e^2]

and that's it. To my understanding I should be able to pull something else out of the square brackets but I tried so long with no success.

Help?
 
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Actually, you want to put something back into the square bracket.

Your function f(x) is going to turn into summing up values of the function that looks like f((b-a)i/n) because you break up the interval into n pieces and sum over the value on each piece. So your objective is to pair up i's and n's
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...

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