Math Problem Statement

For r(x) = -2 / [(3 - 2x)(x + 1)] + 2, do the following: (a) Describe the end behavior. (b) Give the domain and equation of the vertical asymptotes. (c) Describe the local behavior near the vertical asymptotes. (d) Sketch the graph using your answers to (a)-(c). Evaluate at x = 1/4 and label the point on your graph. Label the coordinates of at least one other point on the graph. (e) Give the range of r(x). (f) Solve for x when r(x) = 0.

Solution

Let's go through each part of this problem step-by-step.

Given: r(x)=2(32x)(x+1)+2r(x) = -\frac{2}{(3 - 2x)(x + 1)} + 2

(a) End Behavior

The end behavior is determined by the behavior of r(x)r(x) as x±x \to \pm \infty. Since r(x)r(x) has a rational component with a constant numerator and quadratic terms in the denominator, the function approaches the horizontal asymptote defined by the constant +2+2 as x±x \to \pm \infty.

So, the end behavior: limx±r(x)=2\lim_{x \to \pm \infty} r(x) = 2

(b) Domain and Vertical Asymptotes

To find the domain and vertical asymptotes, we need to identify values of xx that make the denominator zero. The denominator is: (32x)(x+1)(3 - 2x)(x + 1) Setting each factor to zero gives:

  1. 32x=0x=323 - 2x = 0 \Rightarrow x = \frac{3}{2}
  2. x+1=0x=1x + 1 = 0 \Rightarrow x = -1

Thus, vertical asymptotes occur at x=32x = \frac{3}{2} and x=1x = -1.

The domain of r(x)r(x) is all real numbers except x=32x = \frac{3}{2} and x=1x = -1.

(c) Local Behavior Near the Vertical Asymptotes

To describe the behavior near the asymptotes:

  • As x1+x \to -1^{+}, r(x)+r(x) \to +\infty (since the (x+1)(x + 1) term approaches zero positively).

  • As x1x \to -1^{-}, r(x)r(x) \to -\infty (since the (x+1)(x + 1) term approaches zero negatively).

  • As x(32)+x \to \left( \frac{3}{2} \right)^{+}, r(x)r(x) \to -\infty (since (32x)(3 - 2x) approaches zero negatively).

  • As x(32)x \to \left( \frac{3}{2} \right)^{-}, r(x)+r(x) \to +\infty (since (32x)(3 - 2x) approaches zero positively).

(d) Evaluate and Sketch the Graph

To evaluate r(x)r(x) at x=14x = \frac{1}{4}, substitute x=14x = \frac{1}{4} into the function: r(14)=2(3214)(14+1)+2r\left(\frac{1}{4}\right) = -\frac{2}{(3 - 2 \cdot \frac{1}{4})(\frac{1}{4} + 1)} + 2 Simplifying each part:

  1. 3214=312=523 - 2 \cdot \frac{1}{4} = 3 - \frac{1}{2} = \frac{5}{2}
  2. 14+1=54\frac{1}{4} + 1 = \frac{5}{4}

Thus, r(14)=25254+2=2258+2=2825+2=1625+2=501625=3425r\left(\frac{1}{4}\right) = -\frac{2}{\frac{5}{2} \cdot \frac{5}{4}} + 2 = -\frac{2}{\frac{25}{8}} + 2 = -\frac{2 \cdot 8}{25} + 2 = -\frac{16}{25} + 2 = \frac{50 - 16}{25} = \frac{34}{25}

So, r(14)=34251.36r\left(\frac{1}{4}\right) = \frac{34}{25} \approx 1.36.

For sketching, you would plot the asymptotes, the point at x=14x = \frac{1}{4} with y1.36y \approx 1.36, and another point as desired.

(e) Range of r(x)r(x)

Considering the end behavior, vertical asymptotes, and the points evaluated, r(x)r(x) has values approaching infinity near the asymptotes, and approaches 2 as x±x \to \pm \infty. Thus, the range of r(x)r(x) is all real values (,)(-\infty, \infty).

(f) Solve for xx when r(x)=0r(x) = 0

Set r(x)=0r(x) = 0: 2(32x)(x+1)+2=0-\frac{2}{(3 - 2x)(x + 1)} + 2 = 0 Solving for xx: 2(32x)(x+1)=2-\frac{2}{(3 - 2x)(x + 1)} = -2 2(32x)(x+1)=2\frac{2}{(3 - 2x)(x + 1)} = 2 (32x)(x+1)=1(3 - 2x)(x + 1) = 1

Expanding and solving this equation will give the values of xx when r(x)=0r(x) = 0.

Would you like further details on any specific part or help with graphing?

Here are 5 related questions to deepen understanding:

  1. How would the end behavior change if the constant 2 in r(x)r(x) was replaced by another value?
  2. What happens to the function if we change the sign of the numerator in r(x)r(x)?
  3. Can vertical asymptotes intersect with the graph of the function?
  4. How does the range change if we have additional transformations applied to r(x)r(x)?
  5. How can we determine the symmetry of a rational function like r(x)r(x)?

Tip: Always check for points where the function is undefined; these are typically where vertical asymptotes or holes might occur in rational functions.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Asymptotes
End Behavior
Domain and Range

Formulas

Horizontal Asymptote Formula
Vertical Asymptote Analysis
Evaluation of Function Values
Behavior at Infinity

Theorems

Behavior of Rational Functions Near Asymptotes
End Behavior of Rational Functions

Suitable Grade Level

Grades 10-12