Answer:
if f(x) = 3x+4, the rate of change is 4.
if f(x) = 2x+7, the rate of change is 2.
Explanation:
We know that the average rate of change over the interval x=0 to x=8 is:
(f(x2) - f(x1))/x2-x1
Where:
x2 = 8
x1 = 0
if f(x) = 3x+4
so f(8)=3(8)+4 = 28
f(0)=3(0)+4 = 4
Then: (f(x2) - f(x1))/x2-x1 = (28 - 4)/8-0 = 24/8 = 3
On the other hand, if f(x) = 2x+7
f(8) = 2(8)+7 = 23
f(0) = 2(0)+7 = 7
Then: (f(x2) - f(x1))/x2-x1 = Then: 23 - 7/8-0 = 16/8 = 2