Which graph shows the rational function f(x)=x2+3x+2x2−x−2

?(1 point)
Responses

The coordinate grid has its x axis labeled from negative 4 to 6 and its y axis labeled from negative 5 to 5. The graph has a dashed line through left parenthesis 2 comma 5 right parenthesis and left parenthesis 2 comma negative 5 right parenthesis and a dashed line through negative left parenthesis 4 comma 1 right parenthesis and left parenthesis 6 comma 1 right parenthesis. The graph has two curved branches. The left branch starts below the dashed line at y equals 1 and curves down through Left parenthesis negative 2 comma 0 right parenthesis; left parenthesis 0 comma negative 1 right parenthesis; and left parenthesis 1 comma negative 3 right parenthesis; and curves down as it approaches the dashed line at x equals 2. The right branch starts to the right of the dashed line at x equals 2 and curves down through left parenthesis 3 comma 5 right parenthesis; left parenthesis 4 comma 3 right parenthesis; and left parenthesis 6 comma 2 right parenthesis, and curves down as it approaches the dashed line at y equals 1. An open circle is on the left branch of the curve near left parenthesis negative 1 comma negative 0.25 right parenthesis.
Image with alt text: The coordinate grid has its x axis labeled from negative 4 to 6 and its y axis labeled from negative 5 to 5. The graph has a dashed line through left parenthesis 2 comma 5 right parenthesis and left parenthesis 2 comma negative 5 right parenthesis and a dashed line through negative left parenthesis 4 comma 1 right parenthesis and left parenthesis 6 comma 1 right parenthesis. The graph has two curved branches. The left branch starts below the dashed line at y equals 1 and curves down through Left parenthesis negative 2 comma 0 right parenthesis; left parenthesis 0 comma negative 1 right parenthesis; and left parenthesis 1 comma negative 3 right parenthesis; and curves down as it approaches the dashed line at x equals 2. The right branch starts to the right of the dashed line at x equals 2 and curves down through left parenthesis 3 comma 5 right parenthesis; left parenthesis 4 comma 3 right parenthesis; and left parenthesis 6 comma 2 right parenthesis, and curves down as it approaches the dashed line at y equals 1. An open circle is on the left branch of the curve near left parenthesis negative 1 comma negative 0.25 right parenthesis.

The coordinate grid has its x axis labeled from negative 4 to 6 and its y axis labeled from negative 5 to 5. The graph has a dashed line through left parenthesis 2 comma 5 right parenthesis and left parenthesis 2 comma negative 5 right parenthesis and a dashed line through negative left parenthesis 4 comma 1 right parenthesis and left parenthesis 6 comma 1 right parenthesis. The graph has two curved branches. The left branch starts below the dashed line at y equals 1 and curves down through left parenthesis negative 2 comma 0 right parenthesis; left parenthesis 0 comma negative 1 right parenthesis; and left parenthesis 1 comma negative 3 right parenthesis; and curves down as it approaches the dashed line at x equals 2. The right branch starts to the right of the dashed line at x equals 2 and curves down through left parenthesis 3 comma 5 right parenthesis; left parenthesis 4 comma 3 right parenthesis; and left parenthesis 6 comma 2 right parenthesis, and curves down as it approaches the dashed line at y equals 1.
Image with alt text: The coordinate grid has its x axis labeled from negative 4 to 6 and its y axis labeled from negative 5 to 5. The graph has a dashed line through left parenthesis 2 comma 5 right parenthesis and left parenthesis 2 comma negative 5 right parenthesis and a dashed line through negative left parenthesis 4 comma 1 right parenthesis and left parenthesis 6 comma 1 right parenthesis. The graph has two curved branches. The left branch starts below the dashed line at y equals 1 and curves down through left parenthesis negative 2 comma 0 right parenthesis; left parenthesis 0 comma negative 1 right parenthesis; and left parenthesis 1 comma negative 3 right parenthesis; and curves down as it approaches the dashed line at x equals 2. The right branch starts to the right of the dashed line at x equals 2 and curves down through left parenthesis 3 comma 5 right parenthesis; left parenthesis 4 comma 3 right parenthesis; and left parenthesis 6 comma 2 right parenthesis, and curves down as it approaches the dashed line at y equals 1.

The coordinate grid has its x axis labeled from negative 4 to 6 and its y axis labeled from negative 5 to 5. The graph has a dashed line through left parenthesis 2 comma 5 right parenthesis and left parenthesis 2 comma negative 5 right parenthesis and a dashed line through left parenthesis negative 4 comma 1 left parenthesis and left parenthesis 6 comma 1 right parenthesis. The graph has two curved branches. The left branch starts below the dashed line at y equals 1 and curves down through left parenthesis negative 2 comma 0 right parenthesis; left parenthesis 0 comma negative 1 right parenthesis; and left parenthesis 1 comma negative 3 right parenthesis; and curves down as it approaches the dashed line at x equals 2. The right branch starts to the right of the dashed line at x equals 2 and curves down through left parenthesis 3 comma 5 right parenthesis; left parenthesis 4 comma 3 right parenthesis; and left parenthesis 6 comma 2 right parenthesis, and curves down as it approaches the dashed line at y equals 1. An open circle is on the left branch of the curve at left parenthesis negative 2 comma 0 right parenthesis.
Image with alt text: The coordinate grid has its x axis labeled from negative 4 to 6 and its y axis labeled from negative 5 to 5. The graph has a dashed line through left parenthesis 2 comma 5 right parenthesis and left parenthesis 2 comma negative 5 right parenthesis and a dashed line through left parenthesis negative 4 comma 1 left parenthesis and left parenthesis 6 comma 1 right parenthesis. The graph has two curved branches. The left branch starts below the dashed line at y equals 1 and curves down through left parenthesis negative 2 comma 0 right parenthesis; left parenthesis 0 comma negative 1 right parenthesis; and left parenthesis 1 comma negative 3 right parenthesis; and curves down as it approaches the dashed line at x equals 2. The right branch starts to the right of the dashed line at x equals 2 and curves down through left parenthesis 3 comma 5 right parenthesis; left parenthesis 4 comma 3 right parenthesis; and left parenthesis 6 comma 2 right parenthesis, and curves down as it approaches the dashed line at y equals 1. An open circle is on the left branch of the curve at left parenthesis negative 2 comma 0 right parenthesis.

The coordinate grid has its x axis labeled from negative 4 to 6 and its y axis labeled from negative 5 to 5 and a dashed line through left parenthesis 2 comma 5 right parenthesis and left parenthesis 2 comma negative 5 right parenthesis. The graph has a dashed line through left parenthesis negative 4 comma 0 right parenthesis and left parenthesis 6 comma 0 right parenthesis. The graph has two curved branches. The left branch starts below the dashed line at the y axis and curves down through left parenthesis negative 2 comma negative 1 right parenthesis; left parenthesis 0 comma negative 2 right parenthesis; and left parenthesis 1 comma negative 4 right parenthesis; and curves down as it approaches the dashed line at x equals 2. The right branch starts to the right of the dashed line at x equals 2 and curves down through left parenthesis 3 comma 4 right parenthesis; left parenthesis 4 comma 2 right parenthesis; and left parenthesis 6 comma 1 right parenthesis and curves down as it approaches the dashed line at the y axis.

1 answer

To analyze the rational function \( f(x) = \frac{x^2 + 3x + 2}{2x^2 - x - 2} \), we first need to simplify it and find its characteristics, including vertical and horizontal asymptotes.

  1. Factoring the numerator and denominator:
    • The numerator \( x^2 + 3x + 2 \) factors to \( (x + 1)(x + 2) \).
    • The denominator \( 2x^2 - x - 2 \) factors to \( (2x + 3)(x - 2) \) (you can verify this by polynomial long division if necessary).

Thus, we can re-write \( f(x) = \frac{(x + 1)(x + 2)}{(2x + 3)(x - 2)} \).

  1. Finding vertical asymptotes:

    • The vertical asymptotes occur where the denominator is zero (and the numerator is non-zero).
    • Setting \( 2x + 3 = 0 \) gives \( x = -\frac{3}{2} \) and \( x - 2 = 0 \) gives \( x = 2 \).
  2. Finding horizontal asymptotes:

    • Since the degree of the numerator (2) is equal to the degree of the denominator (2), we look at the leading coefficients. The horizontal asymptote is given by the ratio of the leading coefficients, which is \( \frac{1}{2} \).
  3. Behavior at critical points:

    • As \( x \) approaches the vertical asymptote at \( x = 2 \), we can examine the behavior of the function. Since the numerator will be non-zero when \( x = 2 \) (as it factors are linear and won't be zero), the function heads to either positive or negative infinity depending on the direction from which \( x \) approaches 2.
    • Analyzing limits directly on either side of the asymptote would confirm which direction the graph will go.
  4. Intercepts:

    • Set \( f(x) = 0 \) for the x-intercepts: \( (x + 1)(x + 2) = 0 \) gives \( x = -1 \) and \( x = -2 \).
    • Find \( f(0) \) for the y-intercept: \( f(0) = \frac{(0 + 1)(0 + 2)}{(2 \cdot 0 + 3)(0 - 2)} = \frac{2}{-6} = -\frac{1}{3} \).

Using all of this information, we can determine that the graph should exhibit the following characteristics:

  • Vertical asymptote at \( x = 2 \) and \( x = -\frac{3}{2} \).
  • Horizontal asymptote at \( y = \frac{1}{2} \).
  • Curves that cross the x-axis at \( x = -1 \) and \( x = -2 \) and go towards the asymptotes as \( x \) approaches the vertical lines.

To match these characteristics with the descriptions of the graphs provided, you need to identify the graph that accurately depicts two curved branches, vertical asymptotes (at \( x = 2 \) and likely \( x = -1.5 \)), a horizontal asymptote at \( y = \frac{1}{2} \), and the correct intercepts.

From your description, the candidate graph with the correct features should be the one showing:

  • Vertical dashed lines at the corresponding x-values,
  • Curved branches approaching these asymptotes,
  • The specific intercepts at the right coordinates.

Please check your descriptions again against these characteristics to find the correct response.