: f(x) g(x) . , :
. :
y(x)=f(u(x)) f(u) u(x),
y(x)=f(u(x))u(x).
. .
:
-:
- =
-
.
y`=f(x)*U`, yx`=yU`*Ux`, dy/dx=dy/dU=dU/dx
:
-.
y=f(x), x=j(y) - -.
- ,
= 0, - =
-, .. xy`=1/yx`.
Dy/Dx=1/(Dy/Dx) -
, ,
= :
lim(Dy/Dx)=1/(lim(Dy/Dx), .. yx`=1/xy
f`(x)=1/j`(x)
: