Math Problem Statement

Find the horizontal and vertical asymptotes of the curve. You may want to use a graphing calculator (or computer) to check your work by graphing the curve and estimating the asymptotes. (Enter your answers as comma-separated lists. If an answer does not exist, enter DNE.)

y = 

x3 − x

x2 − 4x + 3   x=

1,3    y=

x+4

Solution

We are given the rational function:

y=x3xx24x+3y = \frac{x^3 - x}{x^2 - 4x + 3}

We need to find the horizontal and vertical asymptotes of this curve. Let's go step by step.

Step 1: Vertical Asymptotes

Vertical asymptotes occur where the denominator of the rational function is zero (and the numerator is not zero at the same point). To find the vertical asymptotes, we solve:

x24x+3=0x^2 - 4x + 3 = 0

This is a quadratic equation, which we can factor:

(x1)(x3)=0(x - 1)(x - 3) = 0

So, the vertical asymptotes are at x=1x = 1 and x=3x = 3.

Step 2: Horizontal Asymptotes

To find horizontal asymptotes, we look at the degrees of the numerator and denominator. The degree of the numerator is 3 (since the highest power of xx is x3x^3), and the degree of the denominator is 2 (since the highest power of xx is x2x^2).

Since the degree of the numerator is higher than the degree of the denominator, there is no horizontal asymptote. Instead, there is an oblique (slant) asymptote, which can be found by performing polynomial long division.

Step 3: Oblique (Slant) Asymptote

To find the slant asymptote, we divide x3xx^3 - x by x24x+3x^2 - 4x + 3 using long division. The result of this division will give us the equation of the oblique asymptote.

Polynomial Long Division:

x3xx24x+3\frac{x^3 - x}{x^2 - 4x + 3}

  1. Divide x3x^3 by x2x^2, which gives xx.
  2. Multiply xx by x24x+3x^2 - 4x + 3, which gives x34x2+3xx^3 - 4x^2 + 3x.
  3. Subtract this from x3xx^3 - x, which gives 3x24x3x^2 - 4x.
  4. Divide 3x23x^2 by x2x^2, which gives 33.
  5. Multiply 33 by x24x+3x^2 - 4x + 3, which gives 3x212x+93x^2 - 12x + 9.
  6. Subtract this from 3x24x3x^2 - 4x, which gives 8x98x - 9.

The quotient is x+3x + 3, and the remainder is 8x9x24x+3\frac{8x - 9}{x^2 - 4x + 3}. As xx becomes large, the remainder approaches 0, so the slant asymptote is:

y=x+3y = x + 3

Final Answers:

  • Vertical Asymptotes: x=1,3x = 1, 3
  • Horizontal Asymptotes: DNE (but there is a slant asymptote)
  • Slant Asymptote: y=x+3y = x + 3

Would you like a detailed explanation of any step?

5 Related Questions:

  1. How do you determine when a rational function has a horizontal asymptote?
  2. What is the difference between vertical and horizontal asymptotes?
  3. How do you perform polynomial long division for rational functions?
  4. How do slant asymptotes differ from horizontal asymptotes?
  5. Can a rational function have both horizontal and slant asymptotes?

Tip:

When the degree of the numerator exceeds the degree of the denominator by exactly one, expect a slant asymptote instead of a horizontal one.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Asymptotes
Polynomial Long Division

Formulas

To find vertical asymptotes, solve denominator = 0
Horizontal asymptotes are determined by comparing degrees of numerator and denominator
Polynomial long division to find slant asymptote

Theorems

Degree rule for asymptotes (horizontal vs slant)
Polynomial long division for slant asymptotes

Suitable Grade Level

Grades 11-12