Math Problem Statement

Determine the slope of the secant line of f for each of the intervals indicated in the table

The function f(x) = x^2 + 6x + 6 is graphed below. Determine the slope of the secant line of f for each of the intervals indicated in the table.

Solution

The function provided is f(x)=x2+6x+6f(x) = x^2 + 6x + 6. To find the slope of the secant line over the interval [2,x2][-2, x_2], we use the formula for the slope of the secant line:

msecant=f(x2)f(2)x2(2)m_{\text{secant}} = \frac{f(x_2) - f(-2)}{x_2 - (-2)}

where f(x)=x2+6x+6f(x) = x^2 + 6x + 6 and f(2)f(-2) needs to be calculated first.

Step 1: Compute f(2)f(-2)

f(2)=(2)2+6(2)+6=412+6=2f(-2) = (-2)^2 + 6(-2) + 6 = 4 - 12 + 6 = -2

Now, using f(2)=2f(-2) = -2, we can calculate the secant slopes for each given x2x_2 in the table.

Step 2: Calculate the slopes for each x2x_2

  1. For x2=1x_2 = -1: f(1)=(1)2+6(1)+6=16+6=1f(-1) = (-1)^2 + 6(-1) + 6 = 1 - 6 + 6 = 1 Slope: msecant=f(1)f(2)1(2)=1(2)1+2=31=3m_{\text{secant}} = \frac{f(-1) - f(-2)}{-1 - (-2)} = \frac{1 - (-2)}{-1 + 2} = \frac{3}{1} = 3

  2. For x2=1.9x_2 = -1.9: f(1.9)=(1.9)2+6(1.9)+6=3.6111.4+6=1.79f(-1.9) = (-1.9)^2 + 6(-1.9) + 6 = 3.61 - 11.4 + 6 = -1.79 Slope: msecant=f(1.9)f(2)1.9(2)=1.79(2)1.9+2=0.210.1=2.1m_{\text{secant}} = \frac{f(-1.9) - f(-2)}{-1.9 - (-2)} = \frac{-1.79 - (-2)}{-1.9 + 2} = \frac{0.21}{0.1} = 2.1

  3. For x2=1.99x_2 = -1.99: f(1.99)=(1.99)2+6(1.99)+6=3.960111.94+6=1.9799f(-1.99) = (-1.99)^2 + 6(-1.99) + 6 = 3.9601 - 11.94 + 6 = -1.9799 Slope: msecant=f(1.99)f(2)1.99(2)=1.9799(2)1.99+2=0.02010.01=2.01m_{\text{secant}} = \frac{f(-1.99) - f(-2)}{-1.99 - (-2)} = \frac{-1.9799 - (-2)}{-1.99 + 2} = \frac{0.0201}{0.01} = 2.01

  4. For x2=1.999x_2 = -1.999: f(1.999)=(1.999)2+6(1.999)+6=3.99600111.994+6=1.997999f(-1.999) = (-1.999)^2 + 6(-1.999) + 6 = 3.996001 - 11.994 + 6 = -1.997999 Slope: msecant=f(1.999)f(2)1.999(2)=1.997999(2)1.999+2=0.0020010.001=2.001m_{\text{secant}} = \frac{f(-1.999) - f(-2)}{-1.999 - (-2)} = \frac{-1.997999 - (-2)}{-1.999 + 2} = \frac{0.002001}{0.001} = 2.001

Final Secant Slopes:

  • For x2=1x_2 = -1, the slope is 33.
  • For x2=1.9x_2 = -1.9, the slope is 2.12.1.
  • For x2=1.99x_2 = -1.99, the slope is 2.012.01.
  • For x2=1.999x_2 = -1.999, the slope is 2.0012.001.

Let me know if you'd like more details or have any questions!

Here are some relative questions:

  1. How is the secant line different from the tangent line?
  2. What does the secant slope approach as x2x_2 approaches 2-2?
  3. How can the concept of the derivative be explained through secant slopes?
  4. What does the slope of the tangent line tell us about a function at a point?
  5. How can secant lines help estimate instantaneous rates of change?

Tip: As x2x_2 gets closer to 2-2, the secant slope approaches the derivative at x=2x = -2, which gives the slope of the tangent line.

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Math Problem Analysis

Mathematical Concepts

Algebra
Calculus
Quadratic Functions
Secant Lines

Formulas

Slope of the secant line: m_secant = (f(x2) - f(x1)) / (x2 - x1)
Quadratic function: f(x) = ax^2 + bx + c

Theorems

Secant Line Slope Theorem

Suitable Grade Level

Grades 10-12