1. ∫∫∫E6xy dV, where E lies under the plane z = 1 + x + y Apparently according to a classmate, the limits are: -1≤x≤0, -1-x≤y≤0, and 0≤z≤ 1+x+y I know how to get z. But I am confused for y and x. To solve the limits of y, you would plug in 0 for z, getting y = -1 - x. But why is the upper bound 0? Same for x. I assume you plug in 0 for both y and z when solving for x, resulting in x = -1. I am not sure why the upper bound is 0.