Answer:
Step-by-step explanation:
Recall the following: x = 15u+15v, y = -60u+15v. So, x-y = 75u. Then u = (x-y)/75. 4x+y = 75v. Then v = (4x+y)/75.
We will see how this transformation maps the region R to a new region in the u-v domain. To do so, we will see where the transformation maps the vertices of the region.
(-1,4) -> ((-1-4)/75,(4(-1)+4)/75) = (-1/15, 0)
(1,-4)->(1/15,0)
(3,-2)->(1/15,2/15)
(1,6)->(-1/15,2/15)
That is, the new region in the u-v domain is a rectangle where .
We will calculate the jacobian of the change variables. That is
(we are calculating the determinant of this matrix). The matrix is
(the in-between calculations are omitted).
We will, finally, do the calculations.
Recall that
We will use the change of variables theorem. So,
This si because we are expressing the original integral in the new variables. We must multiply by the jacobian to guarantee that the change of variables doesn't affect the value of the integral. Then,