Hey there, this is my first post, hopefully I don't screw anything up. 1. The problem statement, all variables and given/known data Suppose that ∫ ∫D f(x, y) dA = 4 where D is the disk x2 +y2 ≤ 16. Now suppose E is the disk x2 + y2 ≤ 144 and g(x,y) = 3 f( [x/3], [y/3] ). What is the value of ∫ ∫E g(x, y) dA? 2. Relevant equations 3. The attempt at a solution Well, I figured switching the surface of integration into polar coordinates might be a good idea, but that didn't really lead anywhere. I figured that ∫ (0,4) f(x/3,y/3) would probably be 4/2pi since the limits of integration of the outside integral are usually 0 to 2pi and often have no variables in the function. I also noticed that the fuction in the second double integral was just multiplied by three but didn't know if I could just say that 3*f(x/3,y/3) was equal to f(x,y)... I'm thinking no. That's as far as my thinking went, I couldn't fathom where to go. Thanks for any help.