Calculus
posted by Will .
f(x)=x^2x+3 , n=6 , a=0, b=3
find LRAM, RRAM, and MRAM
for x is greater than or equal to a or less than or equal to b

You are going to do 6 rectangles between x = 0 and x = 3
for LRAM, you use the height at the left.
(I am not going to calculate them for you)
so use
f(0)=
f(.5)=
f(1)=
f(1.5)=
f(2)=
f(2.5)=
for the heights
The base of each rectangle will be 3/6 = .5
add those all up and multiply by .5
Now to do it for RRAM
use:
f(.5)=
f(1)=
......
f(3) =
then add those 6 up and multiply by .5
o do it for the middle points use
f(1/4)=
f(3/4) =
f(1 1/4) =
.......
f(2 3/4 )=
and again multiply by .5, the base of each rectangle 
RRAM:20.99735189
LRAM:21.72280649