Chapter 2: Problem 34
(a) Find the vertical asymptotes of the function $$y=\frac{x^{2}+1}{3 x-2 x^{2}}$$ (b) Confirm your answer to part (a) by graphing the function.
Short Answer
Expert verified
Vertical asymptotes are at \( x = 0 \) and \( x = \frac{3}{2} \). Graphing confirms these asymptotes.
Step by step solution
01
Determine the Criteria for Vertical Asymptotes
Vertical asymptotes occur where the denominator of a rational function equals zero, provided that the numerator is not also zero at those values. For the function \( y = \frac{x^2 + 1}{3x - 2x^2} \), set the denominator equal to zero: \( 3x - 2x^2 = 0 \).
02
Solve the Denominator Equation
To solve for \( x \) where the denominator is zero, rearrange it as \( -2x^2 + 3x = 0 \). Factor out \( x \) to get \( x(3 - 2x) = 0 \). This gives the solutions \( x = 0 \) and \( x = \frac{3}{2} \).
03
Check the Numerator at These Points
Next, check the numerator at \( x = 0 \) and \( x = \frac{3}{2} \). The numerator is \( x^2 + 1 \), which equals 1 at \( x = 0 \) and \( \left(\frac{3}{2}\right)^2 + 1 = \frac{9}{4} + 1 = \frac{13}{4} \) at \( x = \frac{3}{2} \). Since neither evaluation yields zero, both points are vertical asymptotes for the function.
04
Graph the Function to Confirm
Graph the function \( y = \frac{x^2 + 1}{3x - 2x^2} \). Check that as \( x \) approaches the vertical asymptotes \( x = 0 \) and \( x = \frac{3}{2} \), the value of \( y \) approaches infinity or negative infinity, confirming these are indeed the vertical asymptotes.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Rational Functions
Rational functions are a type of function represented by the ratio of two polynomials. They take the form \( y = \frac{P(x)}{Q(x)} \), where \( P(x) \) and \( Q(x) \) are both polynomials and \( Q(x) eq 0 \). It is important that the denominator is not zero as division by zero is undefined.
In the given function \( y = \frac{x^2 + 1}{3x - 2x^2} \), \( x^2 + 1 \) is the numerator and \( 3x - 2x^2 \) is the denominator. Rational functions can have horizontal, vertical, or slant asymptotes, which help describe their graphs.
In the given function \( y = \frac{x^2 + 1}{3x - 2x^2} \), \( x^2 + 1 \) is the numerator and \( 3x - 2x^2 \) is the denominator. Rational functions can have horizontal, vertical, or slant asymptotes, which help describe their graphs.
- Vertical asymptotes occur where the denominator is zero and the numerator is not.
- Horizontal asymptotes are found based on the degrees of the numerator and denominator.
Denominator
The denominator of a rational function is a crucial part since it defines where the function is undefined. When the denominator equals zero, the function cannot have a finite value. This specific point dictates the existence of vertical asymptotes.
In our example with the denominator \( 3x - 2x^2 \), by setting it to zero, we find the values \( x = 0 \) and \( x = \frac{3}{2} \), indicating possible vertical asymptotes. The process to find these values involves solving the quadratic equation for these points.
In our example with the denominator \( 3x - 2x^2 \), by setting it to zero, we find the values \( x = 0 \) and \( x = \frac{3}{2} \), indicating possible vertical asymptotes. The process to find these values involves solving the quadratic equation for these points.
- Factor the equation \(-2x^2 + 3x = 0\).
- Extract common terms or use the quadratic formula if necessary.
- Verify if the numerator is zero at these points to confirm the asymptotes.
Numerator
The numerator in a rational function influences whether a vertical asymptote truly exists at a point where the denominator is zero.
For our function, \( x^2 + 1 \) is the numerator. Checking this at the points \( x = 0 \) and \( x = \frac{3}{2} \) helps ensure there is no simplification that removes the asymptote.
For our function, \( x^2 + 1 \) is the numerator. Checking this at the points \( x = 0 \) and \( x = \frac{3}{2} \) helps ensure there is no simplification that removes the asymptote.
- Evaluate \( x^2 + 1 \) at \( x = 0 \): the result is 1.
- Evaluate at \( x = \frac{3}{2} \): the result is \( \frac{13}{4} \).
Graphing Functions
Graphing functions like rational functions allows you to visually confirm properties like vertical asymptotes.
To graph \( y = \frac{x^2 + 1}{3x - 2x^2} \), observe how \( y \) behaves as \( x \) approaches the vertical asymptotes at \( x = 0 \) and \( x = \frac{3}{2} \).
To graph \( y = \frac{x^2 + 1}{3x - 2x^2} \), observe how \( y \) behaves as \( x \) approaches the vertical asymptotes at \( x = 0 \) and \( x = \frac{3}{2} \).
- As \( x \to 0^+ \), \( y \to +\infty \) and as \( x \to 0^- \), \( y \to -\infty \).
- Similarly, as \( x \to \frac{3}{2}^+ \), \( y \to -\infty \), and \( x \to \frac{3}{2}^- \), \( y \to +\infty \).