Math Problem Statement

Given the function f, of, x, equals, minus, x, squared, plus, 5, x, plus, 14f(x)=−x2+5x+14, determine the average rate of change of the function over the interval 0, is less than or equal to, x, is less than or equal to, 90≤x≤9.

Solution

To determine the average rate of change of the function f(x)=x2+5x+14f(x) = -x^2 + 5x + 14 over the interval 0x90 \leq x \leq 9, we use the formula for the average rate of change of a function over an interval:

Average rate of change=f(b)f(a)ba\text{Average rate of change} = \frac{f(b) - f(a)}{b - a}

where a=0a = 0 and b=9b = 9.

Step 1: Find f(0)f(0)

f(0)=(0)2+5(0)+14=14f(0) = -(0)^2 + 5(0) + 14 = 14

Step 2: Find f(9)f(9)

f(9)=(9)2+5(9)+14=81+45+14=22f(9) = -(9)^2 + 5(9) + 14 = -81 + 45 + 14 = -22

Step 3: Apply the formula for the average rate of change

Average rate of change=f(9)f(0)90=22149=369=4\text{Average rate of change} = \frac{f(9) - f(0)}{9 - 0} = \frac{-22 - 14}{9} = \frac{-36}{9} = -4

Thus, the average rate of change of the function over the interval 0x90 \leq x \leq 9 is 4-4.

Would you like further details or have any questions?

Here are five related questions you can explore:

  1. How does the average rate of change compare to the instantaneous rate of change at x=4.5x = 4.5?
  2. What is the significance of a negative average rate of change?
  3. How would the rate of change differ over a smaller interval, such as 0x50 \leq x \leq 5?
  4. Can you derive the equation of the tangent line to f(x)f(x) at x=0x = 0?
  5. What is the vertex of the parabola represented by f(x)f(x), and how does it relate to the rate of change?

Tip: The average rate of change of a quadratic function over an interval gives insight into the overall behavior of the curve—whether it rises or falls on average.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Average Rate of Change

Formulas

Average rate of change = (f(b) - f(a)) / (b - a)
Quadratic function: f(x) = ax^2 + bx + c

Theorems

Rate of Change Theorem

Suitable Grade Level

Grades 8-10