The answer would be
x² + 18x + 81 = 44 + 81
To complete the square, we look at the value of b (the coefficient of x). We take half of it, then square it; this is the number that gets added to both sides.
18/2 = 9; 9²=81
Therefore we add 81 to both sides.
14.19 + 13.78 = 27.97 seconds for Ryan
15.77 + 16.24 = 32.01 seconds for Daniel
32.01 - 27.97 = 4.04 seconds greater
When working with functions (of all types), the average rate of change is expressed using function notation:

For the interval from x=7 to x=8,
1. find f(7) and f(8):
2. use given formula:

Answer: the average rate of change for the interval from x=7 to x=8 is 4374.