Question

Consider the function x^2+x-4

Estimate the area between the graph and the x-axis between x=2 and x=4 using four rectangles and right end points.

Answer 1

4 rectangles means 0.5 interval width.
(Assuming they are all the same width)

f(0.5) = -3.25
f(1.0) = -2.00
f(1.5) = -0.25
f(2.0) = +2.00

So, the area is 0.5(-3.25-2.00-0.25+2.00) = -1.75

The area is negative since it's mostly below the x-axis.