f
(
x
,
y
)
=
5
−
1
10
(
x
2
+
y
2
)
,
R
=
[
0
,
5
]
×
[
0
,
5
]
Volume
=
∬
R
f
(
x
,
y
)
d
A
=
250
3
=
83.33333
…
Riemann approximation
≈
46.8750
Number of slices: