f dS
M
1
f(x, y, z) = S x + y + z = 1
(1+x+y)3
z
f(x, y, z) = x + y + S z = x2 + y2
1+4z
z = 4
f(x, y, z) = x + y + z S x2 + y2 + z2 = r2 r > 0
z = 0
f(x, y) = x2 + y2 S x2 + y2 + z2 = r2 r > 0
z = h z = r (0 < h < r)
f(x, y, z) = |xyz| S z = x2 + y2
z = 1
1 1
f(x, y, z) = 8-2z S z = 4- x2- y2
2 2
z = 0
f(x, y, z) = x2 S x2 + y2 + z2 = r2 r > 0
S
(0, 0, 0) r r > 0
(0, 0, 0) r
r r
z = -4 z = r > 0
2