Chapter 3: Problem 48
A function \(f\) has a slant asymptote \(y=m x+b(m \neq 0)\) if \(\lim _{x \rightarrow \infty}[f(x)-(m x+b)]=0\) and/or \(\lim _{x \rightarrow-\infty}[f(x)-(m x+b)]=0\) In exercises \(43-48,\) find the slant asymptote. (Use long division to rewrite the function.) Then, graph the function and its asymptote on the same axes. $$f(x)=\frac{x^{4}-1}{x^{3}+x}$$
Short Answer
Step by step solution
Long Division
Analyzing the Quotient
Formulating the Asymptote
Graphing
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Long Division
- Start with the dividend, which is the polynomial in the numerator. For this function, it's the polynomial \(x^4 - 1\).
- The divisor is the polynomial in the denominator, which for this example is \(x^3 + x\).
- The division process continues by dividing the leading term of the dividend by the leading term of the divisor.
- This will give you the first term of the quotient, which in our example is \(x\).
Polynomial Division
- The quotient represents the main term responsible for defining the slant of the asymptote.
- The remainder, which comprises terms that diminish as \(x\) becomes very large, becomes negligible in determining the asymptote.
Graphing Functions
- First, plot the function \(f(x)\) using a graphing calculator or software. This enables you to get a basic sketch of how the curve behaves.
- Next, plot the slant asymptote \(y = x\), which is a straight line with a slope of 1 passing through the origin.
- Observe how the graph of \(f(x)\) gets closer and closer to this line as \(x\) moves towards positive or negative infinity.
Limits at Infinity
- The remainder \(-\frac{1}{x^2} + \frac{1}{x^4}\) approaches 0 rapidly as these terms diminish.
- This leaves the dominant term \(x\), which aligns with the slant asymptote given by \(y = x\).