Math Problem Statement

Combien d'asymptotes possède la courbe représentative de la fonction f(x) = (x^2 + 2x - 1) / (x^2 + x - 2) ? Déterminer leur(s) équation(s).

Solution

To determine the asymptotes of the function f(x)=x2+2x1x2+x2f(x) = \frac{x^2 + 2x - 1}{x^2 + x - 2}, follow these steps:


Step 1: Identify the domain of f(x)f(x)

The denominator must not equal zero: x2+x2=0x^2 + x - 2 = 0 Factoring: (x+2)(x1)=0(x + 2)(x - 1) = 0 Thus, x2x \neq -2 and x1x \neq 1. The domain is R{2,1}\mathbb{R} \setminus \{-2, 1\}.


Step 2: Vertical asymptotes

Vertical asymptotes occur when the denominator is zero but the numerator is non-zero at those points.

  • At x=2x = -2, the numerator x2+2x1=(2)2+2(2)1=441=10x^2 + 2x - 1 = (-2)^2 + 2(-2) - 1 = 4 - 4 - 1 = -1 \neq 0. Thus, x=2x = -2 is a vertical asymptote.
  • At x=1x = 1, the numerator x2+2x1=12+2(1)1=1+21=20x^2 + 2x - 1 = 1^2 + 2(1) - 1 = 1 + 2 - 1 = 2 \neq 0. Thus, x=1x = 1 is also a vertical asymptote.

Step 3: Horizontal asymptotes

The degree of the numerator and denominator are the same (deg=2\deg = 2). To find the horizontal asymptote, divide the leading coefficients: limx±f(x)=11=1\lim_{x \to \pm\infty} f(x) = \frac{1}{1} = 1 Thus, the horizontal asymptote is y=1y = 1.


Step 4: Summary of asymptotes

The curve has:

  1. Vertical asymptotes at x=2x = -2 and x=1x = 1,
  2. A horizontal asymptote at y=1y = 1.

Let me know if you'd like a detailed graphing explanation or further clarifications.

Related Questions

  1. What happens to the behavior of f(x)f(x) near x=2x = -2 and x=1x = 1?
  2. How would you check for oblique asymptotes for higher-degree functions?
  3. Why does the horizontal asymptote depend only on the leading terms?
  4. How can we graph f(x)f(x) using these asymptotes?
  5. Are there points where f(x)f(x) crosses the horizontal asymptote?

Tip

To confirm your work, always test points near and between the asymptotes to observe the curve's behavior.

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Math Problem Analysis

Mathematical Concepts

Functions and Graphs
Rational Functions
Asymptotes
Polynomial Factorization

Formulas

Horizontal asymptote: y = lim (x → ±∞) f(x)
Vertical asymptote: Denominator = 0 and Numerator ≠ 0

Theorems

Degree Comparison for Horizontal Asymptotes
Properties of Rational Functions

Suitable Grade Level

Grades 10-12