Thread: Riemann Sum Help

Use the values 1,1.5,2,4,5 to subdivide the interval [1,5] into subintervals. Using these subintervals and the right end-points of each subinterval as the sample points, compute a Riemann sum for the integral [1,5] ∫ 2*x^2*ⅆx.


I don't know how to to do this. I try doing it like this:
(4/5)*(f(1)+f(1.5)+f(2)+f(4)) and I get 64.32
The online homework system says its wrong, and I don't know any other way to do it.

How did you get (4/5) as $\displaystyle \Delta{x}$?
The intervals are not at equal distances, you have to multiply each height by a different distance. The proper equation should be:

$\displaystyle (0.5*f(1.5)) + (0.5*f(2)) + (2*f(4)) + (1*f(5)) $

When I solved that I had 120.25

I hope that's the correct answer.