Question 105156
{{{f(x)=x^2}}}
{{{f(x+h)=(x+h)^2}}}
{{{f(x+h)=x^2+2xh+h^2}}} Expand. 
{{{f(x+h)-f(x)=(x^2+2xh+h^2)-x^2}}}
{{{f(x+h)-f(x)=2xh+h^2}}}
{{{(f(x+h)-f(x))/h=(2xh+h^2)/h}}}Simplify. 
{{{(f(x+h)-f(x))/h=2x+h}}}