Question 1118212
I'll do one. Do the others exactly the same way.
Calculate {{{f(a)}}}.
{{{f(a)=f(1)=(1)^2/6=1/6}}}
Calculate {{{f(a+h)}}}
{{{f(a+h)=f(1+1)=f(2)=(2)^2/6=4/6}}} <--- I won't simplify here. 
Calculate average rate of change of function.
{{{ARC=(f(a+h)-f(a))/(a+h-a)=(4/6-1/6)/(2)=(3/6)/2=3/12=1/4}}}
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Do the same for the remaining h values.