Question 443249
Recall that the average rate of change is defined as {{{(f(b)-f(a))/(b-a)}}}

{{{f(1) = (1 -1 + 1)/(1+2) = expr(1/3)}}}
{{{f(-1) = (-1 +1 +1)/ (-1+2) = 1}}}

{{{(expr(1/3) - 1)/(1 -(-1)) =  (expr(-2/3))/2 = highlight(expr(-1/3)))}}}