Question #e2a9c

1 Answer
Feb 19, 2018

#"See explanation"#

Explanation:

#f'(x) = lim_{h->0} (f(x+h) - f(x))/h#
#"Here we have"#
#f(x) = ln(x)#
#=> f'(x) = lim_{h->0} (ln(x+h) - ln(x))/h#
#= lim_{h->0} ln((x+h)/x)/h#
#= lim_{h->0} ln(1+h/x)/h#
#= y#
#=> e^y = lim_{h->0} (1+h/x)^(1/h)#
#= e^(1/x)" (Euler's limit)"#
#=> y = 1/x#
#=> f'(x) = 1/x#