calc
posted by luca .
sketch the region enclosed by the given curves. Decide whether to integrate with respect to x or y. Draw a typical approximating rectangle.
y = 2x + 1, y = 13 − x^2, x = −1, x = 2

since y is a function of x in both cases, it will be easier to integrate along x.
∫[1,2] (13x^2)  (2x+1) dx
integrating along y would require breaking the area into two parts.