Math Problem Statement

Consider the graph of f(x) below, determine the following limits and discuss the continuity of the function at x = -4.

Solution

Analysis of the Problem

We are tasked with analyzing the behavior of f(x)f(x) at x=4x = -4, based on the graph provided, by determining:

  1. The left-hand limit (limx4f(x)\lim_{x \to -4^-} f(x)).
  2. The right-hand limit (limx4+f(x)\lim_{x \to -4^+} f(x)).
  3. The overall limit (limx4f(x)\lim_{x \to -4} f(x)).
  4. The continuity of f(x)f(x) at x=4x = -4.

Step-by-Step Solution

1. Left-hand limit (limx4f(x)\lim_{x \to -4^-} f(x))

The graph shows the behavior of f(x)f(x) as xx approaches 4-4 from the left side:

  • As x4x \to -4^-, the function values increase and approach 2.

Thus: limx4f(x)=2.\lim_{x \to -4^-} f(x) = 2.

2. Right-hand limit (limx4+f(x)\lim_{x \to -4^+} f(x))

The graph shows the behavior of f(x)f(x) as xx approaches 4-4 from the right side:

  • As x4+x \to -4^+, the function values decrease and approach 2.

Thus: limx4+f(x)=2.\lim_{x \to -4^+} f(x) = 2.

3. Overall limit (limx4f(x)\lim_{x \to -4} f(x))

Since the left-hand limit and right-hand limit both exist and are equal: limx4f(x)=limx4+f(x)=2,\lim_{x \to -4^-} f(x) = \lim_{x \to -4^+} f(x) = 2, we conclude: limx4f(x)=2.\lim_{x \to -4} f(x) = 2.

4. Continuity of f(x)f(x) at x=4x = -4

For f(x)f(x) to be continuous at x=4x = -4, three conditions must be satisfied:

  1. f(4)f(-4) must exist.
  2. limx4f(x)\lim_{x \to -4} f(x) must exist.
  3. f(4)f(-4) must equal limx4f(x)\lim_{x \to -4} f(x).

From the graph:

  • The function value at x=4x = -4 is given by the hollow circle at (x,y)=(4,3)(x, y) = (-4, 3), so f(4)=3f(-4) = 3.
  • The overall limit limx4f(x)=2\lim_{x \to -4} f(x) = 2.

Since f(4)limx4f(x)f(-4) \neq \lim_{x \to -4} f(x), the function is not continuous at x=4x = -4.

Final Answer

  1. limx4f(x)=2\lim_{x \to -4^-} f(x) = 2
  2. limx4+f(x)=2\lim_{x \to -4^+} f(x) = 2
  3. limx4f(x)=2\lim_{x \to -4} f(x) = 2
  4. f(x)f(x) is not continuous at x=4x = -4.

Do you want me to elaborate further or analyze another point?
Here are some related questions to deepen understanding:

  1. What is the difference between a limit and a function's value at a point?
  2. Can a function have a limit at a point but still be discontinuous? Explain with examples.
  3. How do removable and jump discontinuities differ in terms of limits and function values?
  4. If f(4)f(-4) were redefined to be 2, would f(x)f(x) be continuous at x=4x = -4?
  5. How does the concept of limits help in defining derivatives?

Tip: Always compare left and right-hand limits when assessing continuity or the existence of a limit!

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Math Problem Analysis

Mathematical Concepts

Limits
Continuity
Piecewise Functions

Formulas

Limit: lim_{x → a} f(x) = L
Continuity at a point: f(a) = lim_{x → a} f(x)

Theorems

Definition of Limit
Continuity at a Point

Suitable Grade Level

Grades 11-12