Chapter 3: Problem 48
In Problems 39-56, use the limit laws to evaluate each limit. $$ \lim _{x \rightarrow-2} \frac{1+x}{1-x} $$
Short Answer
Expert verified
The limit is \(-\frac{1}{3}\).
Step by step solution
01
Identify the Limit Expression
The expression given is \( \lim_{x \rightarrow -2} \frac{1+x}{1-x} \). We need to evaluate this limit as \( x \) approaches \(-2\).
02
Apply Limit to Numerator and Denominator Separately
According to the limit laws, we first consider the limit of the numerator \(1+x\) and the limit of the denominator \(1-x\) separately as \(x\) approaches \(-2\).
03
Evaluate the Limit of the Numerator
Calculate the limit of the numerator expression: \( \lim_{x \rightarrow -2} (1+x) = 1 + (-2) = -1 \).
04
Evaluate the Limit of the Denominator
Calculate the limit of the denominator expression: \( \lim_{x \rightarrow -2} (1-x) = 1 - (-2) = 1 + 2 = 3 \).
05
Apply the Quotient Rule
Using the quotient rule for limits, compute the limit of the entire expression: \( \lim_{x \rightarrow -2} \frac{1+x}{1-x} = \frac{-1}{3} \).
06
Confirm Result is Well-Defined
Ensure the denominator does not approach zero, which it doesn't in this case since \( 1-x \) approaches \(3\). Therefore, the limit exists and is \(-\frac{1}{3}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quotient Rule
The Quotient Rule is a fundamental principle in calculus for handling limits of fractions. When you're working with the limit of a fraction, like the one we have \(\lim_{x \rightarrow -2} \frac{1+x}{1-x}\), the quotient rule tells us how to break it down. The rule states that if both the numerator and denominator have defined limits as they approach a certain point, and the limit of the denominator is not zero, then we can find the overall limit of the fraction by:
- Taking the limit of the numerator.
- Taking the limit of the denominator.
- Dividing these two results.
Limit Evaluation
Limit evaluation builds the bridge between variable unknowns and fixed results. It's like predicting the behavior of a mathematical function as it approaches a specific point. In our exercise, we were asked to evaluate \(\lim_{x \rightarrow -2} \frac{1+x}{1-x}\). To do this, we broke the problem into smaller, more manageable parts.First, we evaluated the numerator and the denominator separately. This is where limit laws come in handy; they help simplify such complex expressions. As \(x\) approaches \(-2\), the numerator \(1+x\) becomes \(-1\), and the denominator \(1-x\) becomes \(3\). Together, these steps show how we predictably transformed the expression into a simple fraction result using basic arithmetic.
Applied Calculus
Applied Calculus showcases how calculus tools are used to solve real-world problems and more complex mathematical equations. In the context of our limit example, it gives us a method to compute exact numbers for seemingly ambiguous or undefined expressions. It allows us to:
- Systematically deconstruct equations.
- Apply rules like the product, sum, and quotient rules where necessary.
- Confirm our results by checking our assumptions and calculations.