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Multiple Choice
Given the function , find the largest value of such that if , then .
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Verified step by step guidance
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Step 1: Begin by understanding the problem. We are tasked with finding the largest value of δ such that if |x - 4| < δ, then |x - 2| < 0.4. This involves analyzing the relationship between the two absolute inequalities.
Step 2: Rewrite the inequality |x - 4| < δ in terms of x. This means x must lie within the interval (4 - δ, 4 + δ). Similarly, rewrite the inequality |x - 2| < 0.4, which implies x must lie within the interval (2 - 0.4, 2 + 0.4) or (1.6, 2.4).
Step 3: To ensure that |x - 2| < 0.4 is satisfied whenever |x - 4| < δ, the interval (4 - δ, 4 + δ) must be entirely contained within the interval (1.6, 2.4). This means the endpoints of the interval defined by |x - 4| < δ must not exceed the bounds of (1.6, 2.4).
Step 4: Solve for δ by setting the boundaries. For the left endpoint, 4 - δ ≥ 1.6, which simplifies to δ ≤ 2.4. For the right endpoint, 4 + δ ≤ 2.4, which simplifies to δ ≤ 2.4. The largest δ that satisfies both conditions is δ = 2.4.
Step 5: Verify the solution by substituting δ = 2.4 into the inequality |x - 4| < δ and checking that it ensures |x - 2| < 0.4. This confirms that δ = 2.4 is the correct and largest value.