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I do not understand how to start this problem. I know I have to integrate from 0 to 1 and that n=3 but thats all. Hints/clues appreciated! enter image description here

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Do you know what a Riemann sum is? – Nameless Nov 24 '12 at 18:55
i know n=3, i am confused at what the integrand is myself. – gt2 Nov 24 '12 at 18:59

Hint - Check the different sums given in (a)-(e), and take into account that:

== The function must be evaluated in points of the given subintervals $\,[x_i,x_{i+1}]\subset [0,1]\,$ , and way more important:

== Every value of the function must be multiplied by the correspoding subinterval's length!

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then only B would be the correct answer? – gt2 Nov 24 '12 at 21:39
Yes, indeed (b). Can you explain why the $\,2\,$ before the first summand, though? Also observe that (c) almost makes it...what's the problem with it, though? – DonAntonio Nov 24 '12 at 21:43

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