Question 946213
{{{(f(x)-f(a))/(x-a)=C}}}
So then,
{{{f(x)-f(a)=C(x-a)}}}
{{{f(x)=f(a)+Cx-Ca}}}
{{{f(x)=Cx+(f(a)-Ca)}}}
Compare this to a linear equation,
{{{f(x)=mx+b}}}
So then,
{{{m=C}}}
and
{{{b=f(a)-Ca}}}
So f(x) is a linear function.