. y=logax
Dy = loga(x+Dx)-logax = loga(1+Dx/x) = 1 loga(1+Dx/x) = 1loga(1+t) = 1 loga(1+t)1/t
Dx Dx Dx x Dx/x x t x
t=Dx/x logax = , : (log)¢= 1( log(lim(1+t)1/t) = 1 logae= 1.
x t0 x x lna
.
= =log.
¢= 1 = 1 =ylna
x¢y 1/ylna
=, ()¢=lna.
.
= >0 =alnx. ()¢=(alnx)¢= alnx(alnx)¢=*/=-1 x<0.
.
sin-sinb=2sin[(a-b)/2]*cos[(a+b)/2], cos x
(sin)¢=lim sin (+D) sin = lim 2sin(D/2) cos(+D/2) =
Dx0 Dx Dx0 Dx
=lim sin(D/2) cos(+D/2) = cos x
Dx0 Dx/2
cos x tg x cos x=sin(x-p/2), .
, (sin )¢=cos x, (cos x)¢= - sin x, (tg x)¢=1/cos2 x.
.
=arcsinx =sin. , (arcsinx)¢x= 1 = 1 = 1 = 1
(siny)¢y cosy Ö1-sin2xØ Ö1-x2Ø
. (arcsinx)¢=1/Ö1-x2Ø, (arccosx)¢= - 1/Ö1-x2Ø, (arctgx)¢=-1/(x2+1).
12.
( ). , (=0) (=∞). ƒ() g() , →. ,
( ),
:
:
, ƒ() g() = . , , ƒ() g() , : ƒ() = g()=0.
ƒ() g() , . , ƒ() = ƒ(b)=0,
, . → → , ƒ()→0 g()→0 (, |ƒ()|→+∞, |g()|→+∞), →.
, , .
0.
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