To determine which function has a negative estimated average rate of change over the interval \([0.1, 0.6]\), we can calculate the average rate of change for both functions over that interval.
1. Exponential Function: \( y = 9(13)^x \)
The average rate of change from \( x = 0.1 \) to \( x = 0.6 \) is given by:
\[ \text{Average Rate of Change} = \frac{f(b) - f(a)}{b - a} \]
where \( a = 0.1 \) and \( b = 0.6 \).
Calculating \( f(0.1) \):
\[ f(0.1) = 9(13)^{0.1} \approx 9 \times 1.3499 \approx 12.1491 \]
Calculating \( f(0.6) \):
\[ f(0.6) = 9(13)^{0.6} \approx 9 \times 4.0936 \approx 36.8424 \]
Now, we calculate the average rate of change:
\[ \text{Average Rate of Change}_{\text{exp}} = \frac{36.8424 - 12.1491}{0.6 - 0.1} = \frac{24.6933}{0.5} = 49.3866 \]
2. Quadratic Function: \( y = 9x^2 + 13x \)
Now, let's calculate the average rate of change for the quadratic function:
Calculating \( g(0.1) \):
\[ g(0.1) = 9(0.1)^2 + 13(0.1) = 9(0.01) + 1.3 = 0.09 + 1.3 = 1.39 \]
Calculating \( g(0.6) \):
\[ g(0.6) = 9(0.6)^2 + 13(0.6) = 9(0.36) + 7.8 = 3.24 + 7.8 = 11.04 \]
Now, we calculate the average rate of change:
\[ \text{Average Rate of Change}_{\text{quad}} = \frac{11.04 - 1.39}{0.6 - 0.1} = \frac{9.65}{0.5} = 19.3 \]
Conclusion
- The average rate of change for the exponential function over the interval \([0.1, 0.6]\) is approximately \(49.3866\) (positive).
- The average rate of change for the quadratic function over the same interval is \(19.3\) (also positive).
Since both functions have positive average rates of change, the answer to the question is:
neither function