подробное решение
D: 0 ≤ x ≤ 1 -sqrt(1-x) ≤ y ≤ sqrt(1-x) ∫∫ _(D)xy^3dxdy= ∫ ^(1)_(0)xdx ∫^(sqrt(1-x)_(-sqrt(1-x))y^3dy= = ∫ ^(1)_(0)x [m]\frac{y^4}{4}|^{\sqrt{1-x}}_{-\sqrt{1-x}}[/m]dx= = ∫ ^(1)_(0)x*[m]\frac{(1-x)^2-(1-x)^2}{4}[/m]dx= ∫ ^(1)_(0)x*[red]0[/red]dx=0