The rectangles in the graph below illustrate a right endpoint Riemann sum for $f(x) = \frac{-x^2}{4} + 2x$ on the interval $[2, 6]$.
The value of this right endpoint Riemann sum is ______, and this Riemann sum is there is ambiguity \(\downarrow\) the area of the region enclosed by $y = f(x)$, the x-axis, and the vertical lines $x = 2$ and $x = 6$.
Right endpoint Riemann sum for $y = \frac{-x^2}{4} + 2x$ on $[2, 6]$
