Math Problem Statement

3

Consider the function f(x) = 3 / (x - 2) with various tasks including determining asymptotes, creating a table of values near asymptotes, finding domain and range, identifying positive and negative intervals, and sketching the graph.

Solution

Let's go through each part of question 2 for the function f(x)=3x2f(x) = \frac{3}{x - 2}:

a) Vertical Asymptote

The vertical asymptote occurs where the denominator of f(x)f(x) is zero.

Since the denominator is x2x - 2, setting it equal to zero gives: x2=0x=2x - 2 = 0 \Rightarrow x = 2 The vertical asymptote is x=2x = 2.

b) Table of Values Near the Vertical Asymptote

To observe the behavior of f(x)f(x) near x=2x = 2, let's evaluate f(x)f(x) for values approaching 2 from both sides (from the left and right).

xxf(x)=3x2f(x) = \frac{3}{x - 2}
1.9f(1.9)=31.92=30f(1.9) = \frac{3}{1.9 - 2} = -30
1.99f(1.99)=31.992=300f(1.99) = \frac{3}{1.99 - 2} = -300
2.01f(2.01)=32.012=300f(2.01) = \frac{3}{2.01 - 2} = 300
2.1f(2.1)=32.12=30f(2.1) = \frac{3}{2.1 - 2} = 30

As x2x \to 2^-, f(x)f(x) \to -\infty, and as x2+x \to 2^+, f(x)+f(x) \to +\infty.

c) Horizontal Asymptote

The horizontal asymptote is determined by analyzing the behavior of f(x)f(x) as x±x \to \pm \infty.

f(x)=3x23x as xf(x)0f(x) = \frac{3}{x - 2} \approx \frac{3}{x} \text{ as } x \to \infty \Rightarrow f(x) \to 0

The horizontal asymptote is y=0y = 0.

d) Table of Values Near the Horizontal Asymptote

To confirm the end behavior, we can observe values of f(x)f(x) for large positive and negative xx.

xxf(x)=3x2f(x) = \frac{3}{x - 2}
10f(10)=3102=0.375f(10) = \frac{3}{10 - 2} = 0.375
100f(100)=310020.0306f(100) = \frac{3}{100 - 2} \approx 0.0306
-10f(10)=3102=0.25f(-10) = \frac{3}{-10 - 2} = -0.25
-100f(100)=310020.0294f(-100) = \frac{3}{-100 - 2} \approx -0.0294

As x±x \to \pm \infty, f(x)0f(x) \to 0.

e) Domain and Range

  • Domain: All real values of xx except where the denominator is zero. So, x2x \neq 2.

    Domain: x(,2)(2,)x \in (-\infty, 2) \cup (2, \infty)

  • Range: The function can take any real value except for the horizontal asymptote y=0y = 0.

    Range: y(,0)(0,)y \in (-\infty, 0) \cup (0, \infty)

f) Positive and Negative Intervals

To determine the intervals where f(x)f(x) is positive or negative, observe the sign of f(x)=3x2f(x) = \frac{3}{x - 2}:

  • For x<2x < 2, f(x)f(x) is negative.
  • For x>2x > 2, f(x)f(x) is positive.

So:

  • Positive interval: x(2,)x \in (2, \infty)
  • Negative interval: x(,2)x \in (-\infty, 2)

g) Sketch of the Graph

To sketch f(x)=3x2f(x) = \frac{3}{x - 2}:

  1. Plot the vertical asymptote at x=2x = 2 and the horizontal asymptote at y=0y = 0.
  2. Indicate the behavior as xx approaches the asymptotes.
  3. Show the function approaching 00 as x±x \to \pm \infty.

Would you like further assistance with this problem, such as plotting the graph?

Further Questions:

  1. How does the behavior of f(x)f(x) change near the asymptotes for different values of kk in f(x)=kxaf(x) = \frac{k}{x - a}?
  2. What happens to the horizontal asymptote if we change f(x)f(x) to 3xx2\frac{3x}{x - 2}?
  3. How can transformations shift the location of the asymptotes?
  4. In what cases would the function have no horizontal asymptote?
  5. How would you identify any slant asymptotes for a rational function?

Tip:

When analyzing rational functions, always start by identifying asymptotes—they provide a good framework for understanding the function's behavior.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Asymptotes
Domain and Range
Intervals of Positivity and Negativity
Graph Sketching

Formulas

f(x) = 3 / (x - 2)
Vertical asymptote where denominator = 0
Horizontal asymptote analysis for large x values

Theorems

Asymptote Behavior of Rational Functions

Suitable Grade Level

Grades 11-12