Finding Riemann Sum for f(x)=3x^2+3

[Tonyt88]

Homework Statement

Find the Riemann sum associated with f(x)=3 x^2 +3 ,\quad n=3 and the partition
x_0=0,\quad x_1=3,\quad x_2=4,\quad x_3=6,\qquad \mbox{ of } [0,6]
(a) when x_k^{*} is the right end-point of [x_{k-1},x_k]. .

(b) when x_k^{*} is the mid-point of [x_{k-1},x_k]

Homework Equations

I have no idea where to begin.

The Attempt at a Solution

 

[StatusX]

...what is the definition of a Riemann sum for a given tagged partition?