The value of the double integral ∬D 4xy dA is 81/8.
To evaluate the double integral ∬D4xydA, where D is the triangular region with vertices (0,0), (1,2), and (0,3), we can follow these steps:
Determine the limits of integration for x: x ranges from 0 to the x-coordinate of the line connecting (0,0) and (1,2), which is 3/2.
Determine the limits of integration for y: y ranges from 0 to 3.
Set up the double integral in Cartesian coordinates: ∫(0 to 3) ∫(0 to 3/2) 4xy dx dy.
Integrate with respect to x first, treating y as a constant: ∫(0 to 3/2)

dx =
evaluated from x = 0 to x = 3/2 = (9/4)y.
Integrate the result with respect to y: ∫(0 to 3) (9/4)y
dy =
evaluated from y = 0 to y = 3 = 81/8.