Math Problem Statement

Graph the piecewise function f(x) and evaluate the limits at x = -2 and x = 1. Determine if the function is continuous at x = -2.

Solution

Here is a detailed breakdown of the problem parts shown in the image:

Part (a): Graph the function

The function f(x)f(x) is defined piecewise as:

  • 1x1 - x, if x<2x < -2
  • x+6x + 6, if 2x<2-2 \leq x < 2
  • 3-3, if x2x \geq 2

To graph this function:

  1. For x<2x < -2: The function f(x)=1xf(x) = 1 - x is a linear equation with slope 1-1 and y-intercept 11. Plot this segment to the left of x=2x = -2 (not including x=2x = -2).
  2. For 2x<2-2 \leq x < 2: The function f(x)=x+6f(x) = x + 6 is also linear, with slope 11 and y-intercept 66. This part is valid between x=2x = -2 (included) and x=2x = 2 (not included). Include a solid dot at x=2x = -2 and an open circle at x=2x = 2.
  3. For x2x \geq 2: The function is constant f(x)=3f(x) = -3. Plot a horizontal line at y=3y = -3, starting at x=2x = 2 with a solid dot and extending right.

Part (b): Evaluate limx2f(x)\lim_{x \to -2} f(x)

To determine the limit as x2x \to -2:

  • From the left-hand side (x2x \to -2^-), the function follows 1x1 - x, and substituting x=2x = -2 gives 1(2)=31 - (-2) = 3.
  • From the right-hand side (x2+x \to -2^+), the function follows x+6x + 6, and substituting x=2x = -2 gives (2)+6=4(-2) + 6 = 4.

Since the left-hand limit (33) and right-hand limit (44) are not equal, the limit does not exist.

Part (c): Evaluate limx1f(x)\lim_{x \to 1} f(x)

To determine the limit as x1x \to 1:

  • For 2x<2-2 \leq x < 2, the function is f(x)=x+6f(x) = x + 6.
  • Substituting x=1x = 1 into f(x)=x+6f(x) = x + 6 gives 1+6=71 + 6 = 7.

Thus, limx1f(x)=7\lim_{x \to 1} f(x) = 7.

Part (d): Is ff continuous at x=2x = -2?

A function is continuous at x=2x = -2 if:

  1. limx2f(x)\lim_{x \to -2} f(x) exists.
  2. f(2)f(-2) is defined.
  3. limx2f(x)=f(2)\lim_{x \to -2} f(x) = f(-2).

Here:

  • limx2f(x)\lim_{x \to -2} f(x) does not exist (as shown in part (b)).
  • f(2)=(2)+6=4f(-2) = (-2) + 6 = 4 (using the second piece).

Since the limit does not exist, f(x)f(x) is not continuous at x=2x = -2.


Let me know if you'd like a graph or have any specific questions! Here are five related questions to expand on this problem:

  1. How do you determine the left-hand and right-hand limits for piecewise functions?
  2. What are the conditions for a function to be continuous at a specific point?
  3. How can the behavior of piecewise functions affect their limits?
  4. What are some key differences between a limit existing and a function being continuous?
  5. How would the function change if the second piece included x=2x = 2?

Tip: When working with piecewise functions, always pay close attention to open and closed intervals and how they impact limits and continuity!

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Math Problem Analysis

Mathematical Concepts

Piecewise Functions
Limits
Continuity
Graphing Functions

Formulas

f(x) = 1 - x, for x < -2
f(x) = x + 6, for -2 <= x < 2
f(x) = -3, for x >= 2

Theorems

Limit Definition
Continuity Theorem

Suitable Grade Level

Grades 9-11