Question: https://gyazo.com/acce090bee3f6ccc8346b39e2fe5ab4b
My solution and to the part where I do not understand:
https://gyazo.com/72ab1498de0455f79a0497a2734745fe
I feel I am just computing trapezoid sum rather than midpoint sum. How would I get the midpoint sum?
Also the definite integral would be limit of n approaches infinity, but I do not know if I have to put that since we are given the values.
To use the midpoint rule you need the partition $[1,1.8,2.6,3.4,4.2]$ which has four subintervals with midpoints $1.4,2.2,3.0,3.8.$ The length of each subinterval is $0.8,$ so the midpoint approx is $(0.8)[8.6+7.6+6.3+6.5]=23.2.$