|
-
N(x)R(y)dx+M(x)K(y)dy=0 (1)
| - . - . : (1) M(x)K(y)
|
| N(x)/M(x)*dx+K(y)/R(y)*dy=0 (2)
| (2) . - . (1) ()R(y)
| . . (2),
| ∫(N(x)/M(x)*dx)+ ∫(K(y)/R(y)*dy)=0 . (1) ()R(y), ,
| ()R(y)=0
| y=ϕ(x), , (1). , , , , .
| , , , .
| . y(x+1)dx+(y-1)xdy=0.
| . xy, :
| (x+1)/x*dx+(y+1)/y*dy=0;
| dx+(dx/x)+dy+ (dy/y)=0
|
| x+ln|x|+y+ln|y|=c;
| ln|xy|+x+y=c.
| ()R(y) xy=0. x=0, y=0
| , .
| , x=0, y=0 .
|
-
. : (1). . - 2- U(x,y), M(x,y)dx+N(x,y)=du (2), . - (1) du(x,y)=0. - U(x,y)=C=const. , - (1) . - . . - 2- (3). (2) (3), : , . , , : , , , (4) , . .
| 60.1. dy/dx=f(ax+by+c)
- z=ax+by+c.(2)- :dz/dx=a+b*dy/dx. dy/dx - - (1). dz/dy=a+bf(ax+by+c) (2) dz/dx=a+bf(z). - . - - .
| dx=dz/(a+bf(z))
| x=(∫dz//(a+bf(z)))+c-
|
62.
| - : (7). - . (7). : (8), . (7), : - . , , , .
| 61.1. dy/dx=f(y/x)
- -
| u=y/x(1)
| y=u*x(2)
| y,=u,x+u(3)
| .(3) (2) (1), u,x+u=f(u) (4)
| du/dx*x=f(u)-u dx x(f(u)-u)
| du/(f(u)-u)=dx/x
| ∫(du/(f(u)-u))=lnIxI+c
|
1-
. 1- (1) 0 =0, . (2). 0, . . (2). - : = - (), = - ()dx. , : ,
| ln = , y = C*e (3) (2).
|
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