AP Calculus AB and BC glossary
Right Riemann sum
A right Riemann sum uses the right endpoint of each subinterval as the rectangle height. For an increasing function every rectangle rises above the curve, so the sum overestimates the integral; for a decreasing function it underestimates.
Left and right sums bracket the true value whenever the function is monotonic, so computing both gives you an interval that certainly contains the integral.
The mistake
Skipping the wrong endpoint. A right sum uses the last n endpoints and never uses the first data point in a table.
Appears in: Unit 6: Integration and Accumulation