Chapter 2: Problem 14
Find the limits. \begin{equation}\lim _{x \rightarrow 1^{-}}\left(\frac{1}{x+1}\right)\left(\frac{x+6}{x}\right)\left(\frac{3-x}{7}\right)\end{equation}
Short Answer
Expert verified
The limit is 1.
Step by step solution
01
Simplify the Expression
Consider the expression \(\left(\frac{1}{x+1}\right)\left(\frac{x+6}{x}\right)\left(\frac{3-x}{7}\right)\). To simplify it, combine the fractions into a single fraction: \(\frac{(x+6)(3-x)}{x(x+1)\cdot 7}\).
02
Evaluate the Limits of Individual Parts
Evaluate the limits of each part of the simplified fraction as \(x\) approaches 1 from the negative side: \(\lim_{x \to 1^{-}} \frac{x+6}{7x(x+1)}, \lim_{x \to 1^{-}} (3-x)\).
03
Calculate Each Limit Separately
First calculate \(\lim_{x \to 1^{-}} \frac{x+6}{7x(x+1)}\). Substitute in the function: \(x=1\) results in \(\frac{7}{14} = \frac{1}{2}\). For \(\lim_{x \to 1^{-}} (3-x)\) when \(x = 1\), it results in \(2\).
04
Combine the Results of Limits
The entire limit expression becomes \(\lim_{x \to 1^{-}} \left(\frac{1}{2}\right)\left(2\right) = \frac{1}{2} \times 2 = 1\).
05
Conclusion on Limit
Therefore, \(\lim_{x \to 1^{-}} \left(\frac{1}{x+1}\right)\left(\frac{x+6}{x}\right)\left(\frac{3-x}{7}\right)\) simplifies to \(1\) after evaluating the limits of its parts.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding One-Sided Limits
In calculus, one-sided limits describe the value that a function approaches as the variable approaches a specific point from one side only. This means either from the left or the right.
For example, in our exercise, the notation \(x \to 1^{-}\) signifies that we are considering the limit as \(x\) approaches 1 from the left side only.
For example, in our exercise, the notation \(x \to 1^{-}\) signifies that we are considering the limit as \(x\) approaches 1 from the left side only.
- One-sided limits help us examine the behavior of functions that may not be continuous or have different rules on either side of a point.
- They are crucial for understanding discontinuities and defining derivatives.
Simplifying Fractions in Limits
Fraction simplification is a vital skill in evaluating limits, especially for complex expressions like the one given.
By combining multiple fractions into a single fraction, we make it easier to substitute values into the expression.
By combining multiple fractions into a single fraction, we make it easier to substitute values into the expression.
- The product of fractions involves multiplying numerators and denominators separately.
- Our original expression is simplified to \(\frac{(x+6)(3-x)}{x(x+1)\cdot 7}\), where all terms are in one fraction.
Evaluating Limits Step by Step
Once simplified, a key step in solving limit problems is systematically evaluating each part. One needs to handle fractions and numbers separately before combining them.
- Look at specific parts: evaluate \(\lim_{x \to 1^{-}} \frac{x+6}{7x(x+1)}\) and \(\lim_{x \to 1^{-}} (3-x)\).
- Substitute \(x = 1^{-}\) into each part and simplify wherever possible. \(\lim_{x \to 1^{-}} \frac{x+6}{7x(x+1)} \,=\, \frac{1}{2}\) and \(\lim_{x \to 1^{-}} (3-x) \, = \, 2\).
Approaching from the Left
When we approach a limit from the left, it means taking values that are slightly less than the point of interest. This focuses on behavior just before reaching a specific number, like 1 in our problem.
- Values are considered such that they incrementally increase towards but do not exceed the specified point.
- This helps avoid undefined expressions from occurring in the calculation, like division by zero.