Let fxx3 and compute the riemann sum of f over the interval
Let f(x)=x^3 and compute the riemann sum of f over the interval 0,1
Find n=2, n=5, n=10 subintervals
In each case, choose the representative points to be the midpoints of the subintervals
Can you guess at the area of the region under the graph of f on the interval 0,1
Find n=2, n=5, n=10 subintervals
In each case, choose the representative points to be the midpoints of the subintervals
Can you guess at the area of the region under the graph of f on the interval 0,1
Solution
For n = 2, the subintervals are (0,.5) and (.5,1). The length of each subinterval is .5. Using the midpoints of the subintervals as the representative points, the Riemann Sum is .5(.25^3) + .5(.75^3) = .21875 or 7/32 For n = 5, the subintervals are (0,.2), (.2,.4), (.4,.6), (.6,.8), and (.8,1). The length of each subinterval is .2. Using the midpoints of the subintervals as the representative points, the Riemann sum is .2(.1^3) + .2(.3^3) + .2(.5^3) + .2(.7^3) + .2(.9^3) = .245 or 49/200 For n = 10, the subintervals are (0,.1), (.1,.2), (.2,.3), (.3,.4), (.4,.5), (.5,.6), (.6,.7), (.7,.8), (.8,.9), and (.9,1). The length of each subinterval is .1. Using the midpoints of the subintervals as the representative points, the Riemann sum is .1(.05^3) + .1(.15^3) + .1(.25^3) + .1(.35^3) + .1(.45^3) + .1(.55^3) + .1(.65^3) + .1(.75^3) + .1(.85^3) + .1(.95^3) = .24875 or 199/800. Based on the results, the higher n goes, the Riemann Sum gets closer to .25 or 1/4. So that would be a good guess as the area of the region under the graph of f on the interval 0,1. (In fact, it\'s exactly .25 :D)