.D- OY
D={(x,y):a£x£b,j1(x)<y<j2(x)}
xÎ[a,b] ^ OX. , . , AB, , f(x,y)
.
V=AòBS(x)dx, S- .
. . x-.
S(x)=j1(x)òj2(x)f(x,y)dy
:V=aòbdxj1(x)òj2(x)f(x,y)dy
, , :
òDòf(x,y)dS=aòbdxj1(x)òj2(x)f(x,y)dy (1)
.D- OX
D={(x,y):0£y<di,j1(y)£x£j2(y) yÎ[0;d] ^ OY.
S(y)=j1(y)òj2(y)f(x,y)dx
òDòf(x,y)dS=0òddyj1(y)òj2(y)f(x,y)dx (2)
2 ,:
aòbdxj1(x)òj2(x)f(x,y)dy=0òddyj1(y)òj2(y)f(x,y)dx- .
(1) (2) , .
:
1. , ( ), , , .
2. .
.
.D- OY
D={(x,y):a£x£b,j1(x)<y<j2(x)}
xÎ[a,b] ^ OX. , . , AB, , f(x,y)
.
V=AòBS(x)dx, S- .
. . x-.
S(x)=j1(x)òj2(x)f(x,y)dy
:V=aòbdxj1(x)òj2(x)f(x,y)dy
, , :
òDòf(x,y)dS=aòbdxj1(x)òj2(x)f(x,y)dy (1)
.D- OX
D={(x,y):0£y<di,j1(y)£x£j2(y) yÎ[0;d] ^ OY.
S(y)=j1(y)òj2(y)f(x,y)dx
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òDòf(x,y)dS=0òddyj1(y)òj2(y)f(x,y)dx (2)
2 ,:
aòbdxj1(x)òj2(x)f(x,y)dy=0òddyj1(y)òj2(y)f(x,y)dx- .
(1) (2) , .
.
r0 , V, f(x, y, z) V:
Oz V z=z1(x,y) z=z2(x,y), F(x,y)=0 , Oz, .. V={(x,y)ÎS,z1(x,y)£z£z2(x,y)}, S- V Oxy
{}:1) V={(x,y)ÎS,z1(x,y)£z£z2(x,y)} f(x,y,z), ,.. òòòV fdV; 2) òSòdS z1(x,y)òz2(x,y)fdz. :
òòòV f(x,y,z)dV=òSòdxdy z1(x,y)òz2(x,y)f(x,y,z)dz. z( x y ):
z1(x,y)òz2(x,y)f(x,y,z)dz=G(x,y,z) z1(x,y)ç z2(x,y)=G(x,y,z2(x,y))-G(x,y,z1(x,y))=g(x,y).
òSòg(x,y)dxdy