σ, L ƒ(p). σ ∆σ1, ∆σ2, ..., ∆σn.
∆σ 1, ∆δ2, ..., ∆δn. i
n
∑ ƒ (i) ∆δi, .
i=1
max ∆σi→0 ,
x, y, z : (x, y, z) σ.
.
σ z = z(x, y) xoy D.
(xi*, yi*) , D (. ∆Si)
∆Si ∆Si.
. Pi ∆ σ i
Pi = P(xi, yi, zi)
z
0 y
max ∆σi→0 (maxΔSi→0) , D.
. σ : x=x(y,z) y = y(x,z),
:
(.3876) ƒ(z + 2x + 4/3 y) dσ,
σ x/2 + y/3 + z/4 = 1, .
z
4 z = 4(1 x/2 y/3)
0 3
2 y
x
D, .. . xoy
y
3
x/2 + y/3 = 1
0 2 x
2 3(1-x/2)
∫∫ (z + 2x + 4/3y)dδ = ∫ dx ∫ (4(1 x/2 y/3) + 2x + 4/3y) =
σ 0 0
2 3(1-x/2) 2 3(1-x/2) 2 2
∫ dx ∫ 4dy = 4∫ y│ dx = 4*3 ∫ (1-x/2) dx = 12(x x3/4)│ = 12(2 4/4) = 12
0 0 0 0 0 0