What is the average rate of change of the function f(x)=20(1/4)^x from x = 1 to x = 2?

Enter your answer as a decimal. Do not round.

2 answers

it is the slope of the line joining (1,f(1)) and (2,f(2)):

(1,20/4) and (2,20/16)

(20/16 - 20/4)/(2-1) = ?
30?