What is the average rate of change from the interval 1<x<2?

Question

What is the average rate of change from the interval 1<x<2? 

Answer 1

average rate of change = the quotient difference: [f(b)-f(a)]/[b-a)

= [f(b)-f(a)]/2-1

= f(b) -f(a)

=f(2)- f(1)

= slope of the secant line from (a, f(a)) to (b, f(b)), from (2,f(2)) to (1,f(1))