Express the function graphed on the axes below as a piecewise function.

Question image

Understand the Problem

The question is asking how to represent the given graph as a piecewise function, which involves defining the function separately in different intervals based on the graph's segments.

Answer

The piecewise function is: $$ f(x) = \begin{cases} -x - 1 & \text{for } -10 \leq x < -2 \\ \frac{5}{3}x + \frac{1}{3} & \text{for } -2 \leq x < 4 \\ -\frac{5}{3}x + \frac{43}{3} & \text{for } 4 \leq x \leq 10 \end{cases} $$
Answer for screen readers

The piecewise function is given by:

$$ f(x) = \begin{cases} -x - 1 & \text{for } -10 \leq x < -2 \ \frac{5}{3}x + \frac{1}{3} & \text{for } -2 \leq x < 4 \ -\frac{5}{3}x + \frac{43}{3} & \text{for } 4 \leq x \leq 10 \end{cases} $$

Steps to Solve

  1. Identify the intervals for the function segments

Review the graph to identify the intervals on the x-axis where the function changes. The function consists of three main segments:

  • From $x = -10$ to $x = -2$
  • From $x = -2$ to $x = 4$
  • From $x = 4$ to $x = 10$
  1. Determine the equations for each segment

Next, find the equations that describe the function for each of these intervals:

  • Segment 1 ($-10 \leq x < -2$): This segment is linear with endpoints $(-10, 5)$ and $(-2, -3)$.

    The slope $m$ can be calculated: $$ m = \frac{-3 - 5}{-2 + 10} = \frac{-8}{8} = -1 $$ The line equation in point-slope form using $(-2, -3)$: $$ y + 3 = -1(x + 2) $$ Simplifying gives: $$ y = -x - 1 $$

  • Segment 2 ($-2 \leq x < 4$): This segment also is linear with endpoints $(-2, -3)$ and $(4, 7)$.

    The slope $m$ again: $$ m = \frac{7 - (-3)}{4 - (-2)} = \frac{10}{6} = \frac{5}{3} $$ Using point-slope form with $(-2, -3)$: $$ y + 3 = \frac{5}{3}(x + 2) $$ Simplifying gives: $$ y = \frac{5}{3}x + \frac{1}{3} $$

  • Segment 3 ($4 \leq x \leq 10$): This segment is linear with endpoints $(4, 7)$ and $(10, -3)$.

    The slope $m$: $$ m = \frac{-3 - 7}{10 - 4} = \frac{-10}{6} = -\frac{5}{3} $$ Using point-slope form with $(4, 7)$: $$ y - 7 = -\frac{5}{3}(x - 4) $$ Simplifying gives: $$ y = -\frac{5}{3}x + \frac{43}{3} $$

  1. Write the piecewise function

Now, we can piece it together into one function:

$$ f(x) = \begin{cases} -x - 1 & \text{for } -10 \leq x < -2 \ \frac{5}{3}x + \frac{1}{3} & \text{for } -2 \leq x < 4 \ -\frac{5}{3}x + \frac{43}{3} & \text{for } 4 \leq x \leq 10 \end{cases} $$

The piecewise function is given by:

$$ f(x) = \begin{cases} -x - 1 & \text{for } -10 \leq x < -2 \ \frac{5}{3}x + \frac{1}{3} & \text{for } -2 \leq x < 4 \ -\frac{5}{3}x + \frac{43}{3} & \text{for } 4 \leq x \leq 10 \end{cases} $$

More Information

This piecewise function defines the behavior of the graph across different intervals. Each linear segment corresponds to a specific range of x-values, showcasing how functions can change based on their input values.

Tips

  • Incorrectly identifying the intervals: It’s crucial to ensure that the x-intervals are completely covered and correctly defined based on the graph.
  • Forgetting to simplify the line equations: Make sure to expand and simplify your equations fully.
  • Confusion with closed/open endpoints: Pay attention to whether the endpoints are included in the piecewise segments.

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