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Multiple Choice
Given the function , find a number > such that if , then .
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Verified step by step guidance
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Step 1: Start by understanding the problem. You are tasked with finding a value of δ > 0 such that if |x - 1| < δ, then |x² - 1| < 1/2. This involves analyzing the behavior of the function f(x) = x² near x = 1 and ensuring the output deviation is within the specified range.
Step 2: Rewrite the inequality |x² - 1| < 1/2 in terms of the function f(x). This means we need to ensure that the difference between f(x) and f(1) is less than 1/2. Since f(x) = x² and f(1) = 1, the inequality becomes |x² - 1| < 1/2.
Step 3: Factorize the expression |x² - 1| to simplify it. Using the difference of squares formula, we can rewrite |x² - 1| as |(x - 1)(x + 1)|. The inequality now becomes |(x - 1)(x + 1)| < 1/2.
Step 4: Analyze the term |x + 1|. Since we are considering values of x close to 1 (i.e., |x - 1| < δ), the term x + 1 will be close to 2. Approximate |x + 1| ≈ 2 for small δ, which simplifies the inequality to |x - 1| * 2 < 1/2.
Step 5: Solve for δ. Divide both sides of the inequality |x - 1| * 2 < 1/2 by 2 to isolate |x - 1|. This gives |x - 1| < 1/4. Therefore, δ = 1/4 satisfies the condition. However, you should verify other δ values provided in the problem to confirm the correct answer.