Very hard area and definite integral problem

I'm lost on this stuff, can someone work this problem

[1]

Let f(x)= x^2 and compute the Riemann sum of *f *over the interval [2,4], using

a) Two subintervals of equal length (n=2).

b) Five subintervals of equal length (n=5).

c) Ten subintervals of equal length (n=10).

in each case, choose the representative points to be the midpoints of the subintervals.

d) can you guess at the area of the region under the graph of *f *on the interval [2,4]?

[2]

Repeat excercise above, choosing the reresentative points to be the right endpoints of the subintervals.