Solución
∬
S
(
x
i
+
y
j
)
⋅
d
S
=
16
π
\iint_S(x\bold{i}+y\bold{j}) \cdot d\bold{S} = 16\pi
∬
S
(
x
i
+
y
j
)
⋅
d
S
=
16
π