x=rcos φ ; y=r*sin φ
0 ≤ r ≤ 1
0 ≤ φ ≤ (π/2)
= ∫ ^(1)_(0)dr ∫ ^(π/2)_(0)(2rcos φ+r^2sin^3 φ )d φ =
=2 ∫ ^(1)_(0)rdr ∫ ^(π/2)_(0)(cos φ)d φ + ∫ ^(1)_(0)r^3dr ∫ ^(π/2)_(0)(sin^3 φ )d φ =
=2 ∫ ^(1)_(0)rdr ∫ ^(π/2)_(0)(cos φ)d φ + ∫ ^(1)_(0)r^3dr ∫ ^(π/2)_(0)(sin^2 φ )*sin φ d φ
=2 ∫ ^(1)_(0)rdr ∫ ^(π/2)_(0)(cos φ)d φ + ∫ ^(1)_(0)r^3dr ∫ ^(π/2)_(0)(1-cos^2 φ )*sin φ d φ