Question 831350
{{{g(5)=2/5}}}
{{{g(a)=2/a}}}
{{{ARC=(g(5)-g(a))/(5-a)}}}
{{{ARC=(2/5-2/a)/(5-a)}}}
{{{ARC=2(1/5-1/a)/(5-a)}}}
{{{ARC=2(a-5)/5a(5-a)}}}