The ave. r. of c. of a function f(x) on the interval [a,b] is given by:
f(b) - f(a)
a.r.c. = --------------
b - a
Here f(x) = 2x^2 + 4x - 3, a = 1 and b = 6. Therefore,
f(a) = f(1) = 2(1)^2 + 4(1) - 3 = 3, and f(b) = f(6) = 2(6)^2 + 4(6) - 3 = 93
So the a. r. c. is then
93 - 3 90
a.r.c. = ---------- = --------- = 18 (answer)
6-1 5