Answer:
- 2
Step-by-step explanation:
The average rate of change of h(x) in the closed interval [a, b ] is

Here [a, b ] = [1, 8 ], thus
f(b) = f(8) = - 8² + 7(8) + 14 = - 64 + 56 + 14 = 6
f(a) = f(1) = - 1² + 7(1) + 14 = - 1 + 7 + 14 = 20
average rate of change =
=
= - 2
6 feet * 7 feet = 42 feet²
18 feet * 21 feet = 378 feet²
42 feet² was painted for $52
1 feet² will be painted for $52/42
378 feet² will then be painted for: ($52/42) * 378
= $468
Hence 18 feet by 21 feet will be painted for $468
Hope this helps.
Answer:
21
Step-by-step explanation: