Exponential and logarithmic derivatives

Fact: B(x) = bx is continuous.

Fact: B′ (0) = lim ℎ→0 b0+ℎ -b0 ℎ exists.

Fact: there is a unique value 𝒆 such that

E′ (0) = ( 𝒆x ) ′ | x=0 =1

If ℬ(x)= 𝒷x then

ℬ′(x)= ℬ′(0) 𝒷x

If ℰ(x)= ℯx then

ℰ′ ( g(x) ) = ℯ g(x) g′(x)

If x>0 and y=lnx then

y′= [lnx] ′ = 1x

If g(x)>0 and h(x)= ln ( g(x) ) then

h′ (x) = 1 g(x) g′ (x)

Let b>0, b≠1

  • If y= logbx then y′= 1 xlnb
  • If y= bx then y′= bx lnb

Examples

  • ⅆⅆx ℯ sin( x2+5⁢x )
  • ⅆⅆx ( ℯx2 x )
  • ⅆⅆx ln( x2 ⁢sinx )
  • ⅆⅆx ln( x2 ⁢sin( x3+4⁢x ) 2⁢x+1 )
  • ⅆⅆx 2x 3x+1
  • ⅆⅆx log5 ( 4x+9 )

Logarithmic differentiation

  • y= xr
  • y= xx
  • y= ( 2x4+1 ) tanx
  • y= x23 1+x2 x+x3