cos (log x + ex), x > 0
5 5 Logarithmic Differentiation
In this section, we will learn to differentiate certain special class of functions given in
the form
y = f (x) = [u(x)]v (x)
By taking logarithm (to base e) the above may be rewritten as
log y = v(x) log [u(x)]
Using chain rule we may differentiate this to get
1
1
( )
( )
dy
v x
y dx
u x
⋅
=
⋅ u′(x) + v′(x)