Question #69fe4

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Answer 1 · 2017-04-07T10:20:33

See below

For #f(x) = 1/x#:

#f'(x) = lim_(h to 0) (1/(x+h) - 1/x)/h#

# = lim_(h to 0) ((x - (x+h))/(x(x+h)))/h#

# = lim_(h to 0) - (h/(x(x+h)))/h#

# = lim_(h to 0) - 1/(x(x+h)) = -1/x^2#

For #f(x) = x#:

#f'(x) = lim_(h to 0) ((x+h) - x)/h#

#= lim_(h to 0) h/h = 1#

That should be enough, whatever yr question is.