(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

f(x) = 1/x

Proof that the limit of f(x) = 1/3 near 3

the answer provided by the text is: (1/x - 1/3) < e by requiring abs(x-3) < min(6e, 1)

I can see that the text has the right process and therefore it reaches the right answer, but I have done it in a different process which I believe is also correct but to a different answer. Can you see where have I made the mistake in my process?

2. Relevant equations

3. The attempt at a solution

This is my process:

Note:

(1/x - 1/3) = (3-x)/3x

Take

abs(x-3) < 1

=> 2 < x < 4

=> 6 < 3x < 12

=> 1/6 > 1/3x > 1/12

=> abs(1/3x) > 1/12 since 3x > 0

abs( (3-x) / (3x) ) < e

=> abs( (3-x) ( 1/3x) ) < e

Therefore, (1/12)(abs(3-x)) = (1/12)(abs(x-3)) < abs(3-x)abs(1/3x) < e

shows that abs(x-3)/12 < e

or abs(x-3) < e/ 12

therefore, my final answer becomes

(1/x - 1/3) < e by requiring abs(x-3) < min(e/12, 1)

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Proof of the limit f(x) = 1/x is 1/3 near 3

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