Question 322585
{{{f(x) = 1/x}}}
{{{f(x+h) = 1/(x+h)}}}
.
.
.
{{{f(x+h)-f(x)=1/(x+h)-1/x}}}
{{{f(x+h)-f(x)=x/(x(x+h))-(x+h)/(x(x+h))}}}
{{{f(x+h)-f(x)=(x-(x+h))/(x(x+h))}}}
{{{f(x+h)-f(x)=-h/(x(x+h))}}}
.
.
.
{{{(f(x+h)-f(x))/h=-1/(x(x+h))}}}
{{{lim(x->0,(f(x+h)-f(x))/h)=-1/x^2}}}