Examine the Riemann sum below for the area under
How many rectangles were used?
Notice that the index starts at
and ends at .
Also recall that
, where represents number of rectangles.
If the area being approximated is
, what are and ? is easy to spot in a Riemann sum. Now find the end-value, .
General form of a left-endpoint Riemann sum:
You already computed how many rectangles there are part (a).
, so each rectangle has a width of .