Problem

For the function given below, find a formula for the Riemann sum obtained by dividing the interval [0,5] into n equal subintervals and using the right-hand endpoint for each ck. Then take a limit of this sum as n to calculate the area under the curve over [0,5].
f(x)=x2+5
Write a formula for a Riemann sum for the function f(x)=x2+5 over the interval [0,5]. Sn= (Type an expression using n as the variable.)

Answer

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Answer

Calculate the limit, we get 2753.

Steps

Step 1 :First, we need to understand what a Riemann sum is. A Riemann sum is a certain kind of approximation of an integral by a finite sum. It is named after nineteenth century German mathematician Bernhard Riemann. One very common application is approximating the area of functions or lines on a graph, but also the length of curves and other approximations.

Step 2 :For the function f(x)=x2+5 over the interval [0,5], we divide the interval into n equal subintervals. The width of each subinterval is 5n.

Step 3 :We use the right-hand endpoint for each ck. So, ck=5kn for k=1,2,...,n.

Step 4 :Then, the Riemann sum is given by Sn=k=1nf(ck)Δx, where Δx is the width of the subinterval.

Step 5 :Substitute f(ck) and Δx into the formula, we get Sn=k=1n((5kn)2+5)5n.

Step 6 :Simplify the formula, we get Sn=125n3k=1nk2+25nk=1n1.

Step 7 :We know that k=1nk2=n(n+1)(2n+1)6 and k=1n1=n. Substitute these into the formula, we get Sn=1256(n(n+1)(2n+1)n3)+25.

Step 8 :Simplify the formula, we get Sn=1256(2+3n+1n2)+25.

Step 9 :Take the limit of this sum as n, we get limnSn=12562+25.

Step 10 :Calculate the limit, we get 2753.

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