Question

a)If f(x)= x/(x+2), 1 less than or equal to x less than or equal to 4, find the left and right sums for n= 10, 30, and 50.

b)Illustrate by graphing the rectangles in part a.

c)Show that the exact area under f lies between 1.603 and 1.624.

So this is all I know and I'm not sure if it's correct. Help please.

The x-axis of the graph will start at 1 and end at 4, so I will have 4 equal rectangles each with a width of 0.75.

So,
R4= 0.75*(1.75)^2 + 0.75*(2.5)^2 + 0.75*(3.25)^2 + 0.75*(4)^2 = 26.90625

AND,
L4= 0.75*(1)^2 + 0.75*(1.75)^2 + 0.75*(2.5)^2 + 0.75*(3.25)^2 = 15.65625

What is the "n" used for? Where are they getting the 1.603 and 1.624?