Originally Posted by

**colorado** I am learning about using riemann sums to calculate area. I came across this example and it doesn't make much sense to me.

the example is: find the area of the region bounded by y = 16 - x^2 and the x-axis for

1<x<3

where I am getting confused is at the end.....

(30/n)(n)-[8/n^2][1/2(n)(n+1)]-[8/n^3][1/6(n)(n+1)(2n+1)]

= 70/3 - 8/n -4/3n^2

I don't understand where the 70/3 comes from. and I predict that -8/n and -4/3n^2 just coming from simplifying the corresponding -[8/n^2][1/2(n)(n+1)] and -[8/n^3][1/6(n)(n+1)(2n+1)]. thank you.