Find the maximum value of [tex]\(\delta \ \textgreater \ 0\)[/tex] that satisfies the limit claim corresponding to [tex]\(\varepsilon = 0.2\)[/tex], such that [tex]\(0 \ \textless \ |x - c| \ \textless \ \delta\)[/tex] implies [tex]\(|f(x) - L| \ \textless \ 0.2\)[/tex].

Given:
[tex]\[
\lim _{x \rightarrow 2}\left(5-\frac{x}{2}\right)=4
\][/tex]



Answer :

To find the maximum value of [tex]\(\delta > 0\)[/tex] that satisfies the limit claim for [tex]\(\varepsilon = 0.2\)[/tex], let's go through the problem step-by-step.

We are given:
[tex]\[ \lim _{x \rightarrow 2}\left(5-\frac{x}{2}\right)=4 \][/tex]
This means that as [tex]\(x\)[/tex] approaches [tex]\(2\)[/tex], the function [tex]\(f(x) = 5 - \frac{x}{2}\)[/tex] approaches the value [tex]\(4\)[/tex].

We need to find the maximum value of [tex]\(\delta\)[/tex] such that:
[tex]\[ 0 < |x - 2| < \delta \implies |f(x) - 4| < 0.2 \][/tex]

1. Evaluate the inequality [tex]\(|f(x) - 4| < 0.2\)[/tex]:
[tex]\[ |(5 - \frac{x}{2}) - 4| < 0.2 \][/tex]
Simplify the expression inside the absolute value:
[tex]\[ |1 - \frac{x}{2}| < 0.2 \][/tex]

2. Remove the absolute value by considering the bounds:
[tex]\[ -0.2 < 1 - \frac{x}{2} < 0.2 \][/tex]

3. Solve the inequalities to find the bounds for [tex]\(x\)[/tex]:

For the lower bound:
[tex]\[ -0.2 < 1 - \frac{x}{2} \][/tex]
[tex]\[ -1.2 < -\frac{x}{2} \][/tex]
[tex]\[ 1.2 > \frac{x}{2} \][/tex]
[tex]\[ x < 2.4 \][/tex]

For the upper bound:
[tex]\[ 1 - \frac{x}{2} < 0.2 \][/tex]
[tex]\[ 1 - 0.2 < \frac{x}{2} \][/tex]
[tex]\[ 0.8 < \frac{x}{2} \][/tex]
[tex]\[ 1.6 < x \][/tex]

4. Combine the bounds to get the interval for [tex]\(x\)[/tex]:
[tex]\[ 1.6 < x < 2.4 \][/tex]

5. Determine [tex]\(\delta\)[/tex]:

The maximum [tex]\(\delta\)[/tex] is the smallest distance from [tex]\(x = 2\)[/tex] to either endpoint of the interval [tex]\(1.6 < x < 2.4\)[/tex].

[tex]\[ \delta_{\text{lower}} = 2 - 1.6 = 0.4 \][/tex]
[tex]\[ \delta_{\text{upper}} = 2.4 - 2 = 0.4 \][/tex]

Therefore, [tex]\(\delta = \min(\delta_{\text{lower}}, \delta_{\text{upper}}) = 0.4\)[/tex].

So, the maximum value of [tex]\(\delta\)[/tex] that satisfies the given limit claim is:
[tex]\[ \delta = 0.4 \][/tex]

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