- , ' ( - )
- , '
.
1. .
X(x)Y(y)dx+X1(x)Y1(y)dy=0
: (1)
¢, (1), : 1()=0 1()=0.
2. :
P(x, y)dx+Q(x, y)dy=0,
P(x, y) Q(x, y) , ¢ y=u*x (u ).
3. ˳ :
a(x)y¢+b(x)y+c(x)=0
¢ y=u*v,
u ¢
a(x)y¢+b(x)y=0, v .
4. :
) y¢¢=f(x), ¢:
;
) y¢¢=f(), :
;
) y¢¢=f(¢),
: , ¢=.
5. :
) ¢¢=f(x, y¢), ¢=(), :
;
) ¢¢=f(, y¢), ¢=(), :
.
6. ¢ - :
¢¢+()¢+q(x)y=0
=11+22,
1 2 ¢.
7. ¢ - :
¢¢+()¢+q(x)y=f(x) ,
- ¢ ; z ¢ .
8. 1.
¢ ¢¢+¢+qy=0 (p i q - ) k2+pk+q=0.
(a>0,a¹1); d(ln u)=
4) d(sin u)=cos u du; 10) d(arctg u)= ;
5) d(cos u)= -sin u du; 11) d(arcctg u)=
6) d(tg u)= 12) df(u)=f¢(u)du.
15. :
f(x+∆x)-f(x)f¢(x)∆x
16. =f(x), - (d2x)=0:
d2y=''dx2.
55. .
X(x)Y(y)dx+X1(x)Y1(y)dy=0
: (1)
¢, (1), : 1()=0 1()=0.
56.. :
P(x, y)dx+Q(x, y)dy=0,
P(x, y) Q(x, y) , ¢ y=u*x (u ).
57. ˳ :
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a(x)y¢+b(x)y+c(x)=0
¢ y=u*v,
u ¢
a(x)y¢+b(x)y=0, v .