Question 828490
{{{ (f(x+h)-f(x)) / h }}} =
{{{(1/(2(x+h))-1/(2(x)))/h}}}=
{{{((1/(2(x+h))))*(1/h)}}}-{{{((1/(2(x)))*(1/h))}}}
{{{((1/(2h(x+h))))}}}-{{{((1/(2h(x))))}}}
revise to common denominator
{{{((1/(2h(x+h)))*(x/x))}}}-{{{((1/(2h(x))*(x+h)/(x+h)))}}}
{{{((x-(x+h))/(2hx*(x+h))))}}}
{{{(h/(2hx*(x+h))))}}}
{{{(1/(2x*(x+h))))}}}
as h approaches zero
{{{(1/(2x*(x))))}}}
{{{(1/(2x^2)))}}}