Section 15.1: Double Integrals over rectangles

If \(R = [0, 4] \times [-1, 2]\), use a Riemann sum with \(m = 2\), \(n = 3\) to estimate the value of \(\iint_R (1 - xy^2) dA\). Take the sample points to be (a) the lower right corners and (b) the upper left corners of the rectangles.