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Homework Statement
Find f'(c) and the error estimate for the limit:
[tex] f'(c) = \lim_{x \to 0^{+}} \frac {f(c+\Delta x) - f(c)}{\Delta x} [/tex]
I just included that to show that we are working with one (right) sided limit the actual problem is:
[tex] f(x) = \frac {1}{x} \;\; with\;\; c = 3[/tex]
Homework Equations
The error is given by:
[tex] E(\Delta x) = \frac {1}{2}M \Delta x [/tex]
and
[tex] |f''(c)| \leq M [/tex]
The Attempt at a Solution
So this really quite simple, if:
[tex] f(x)= \frac {1}{x} [/tex]
then
[tex] f'(x) = -\frac{1}{x^{2}} [/tex]
and
[tex] f''(x) = \frac {2}{x^{3}}[/tex]
so
[tex] f'(c) = -\frac{1}{9} [/tex]
and
[tex] f''(c) = \frac {2}{27} \Delta x[/tex]
but according to the book the error is suppose to be 1/27 which doesn't really make sense to me. I got f''(x) like so:
[tex] \frac {(x^{2})(0)-(-1)(2x)}{(x^{2})^{2}} [/tex]
[tex] \frac {2x}{x^{4}} [/tex]
[tex] \frac {2}{x^{3}} [/tex]
where did I go wrong?