Chapter 2: Problem 71
You will find a graphing calculator useful for Exercise. Let \(f(x)=\left(x^{2}-1\right) /(|x|-1).\) a. Make tables of the values of \(f\) at values of \(x\) that approach \(c=-1\) from above and below. Then estimate \(\lim _{x \rightarrow-1} f(x).\) b. Support your conclusion in part (a) by graphing \(f\) near \(c=-1\) and using Zoom and Trace to estimate \(y\) -values on the graph as \(x \rightarrow-1.\) c. Find \(\lim _{x \rightarrow-1} f(x)\) algebraically.
Short Answer
Step by step solution
Analyze the Function
Make a Table for Values Approaching -1 from Above
Make a Table for Values Approaching -1 from Below
Estimate the Limit from the Table
Graph the Function and Use Zoom and Trace
Algebraically Find the Limit
Conclude with the Limit
Final Verification
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Calculator
To graph this function, input the equation into a graphing calculator. Focus on the region near \(x = -1\) to understand how the function behaves as \(x\) approaches this critical point.
- Use the "Zoom" feature to closely examine the behavior around \(x = -1\).
- Utilize the "Trace" feature to estimate \(y\)-values when \(x\) is close to \(-1\), which can confirm findings from other methods used to estimate limits.
Limit Calculation
In this exercise, we estimate the limit of \(f(x)\) as \(x\) approaches \(-1\). We make tables with values for \(x\) approaching \(-1\) from both sides, noticing that \(f(x)\) approaches 0. This indicates that \(\lim_{x \to -1} f(x) = 0\).
- Choose values of \(x\) close to \(-1\) like -0.9, -0.99, and -1.1, -1.01.
- Compute \(f(x)\) for each of these values to see how they behave when \(x\) nears \(-1\). This aids in predicting the trend of \(f(x)\).
Function Analysis
However, by rewriting \(x^2 - 1\) as \((x-1)(x+1)\) and analyzing \(|x|-1\), we notice
- For \(x > 1\), \(|x| = x\), simplifying \(f(x)\) to \(x+1\) which indicates a potential removable discontinuity.
- Since \(f(x)\) simplifies to \(x + 1\) as \(x eq 1\), it easily tells us about behavior trends. Hence, analyzing these forms gives understanding of what happens around critical points.
Algebraic Simplification
Simplify \(x^2 - 1\) to \((x-1)(x+1)\). For cases not triggering absolute value adjustments, this technique reformulates problematic expressions.
- In most contexts, \(x-1\) can be canceled, streamlining expressions.
- Resulting in \(f(x) = x + 1\), shows any canceled terms hint at removable discontinuities resolved by limit evaluation.