Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

Question about epsilon - delta proofs?

I have a page of examples of solving epsilon - delta proofs. Upon proving that lim x -> 2 (x^2 + x - 2) = 4, the page says " the right hand side is at the minimum when x + 3 is at its maximum. Since the maximum of x + 3 is 6, we know that,

|x - 2| < e / |x + 3| < e / 6

My question is if the maximum of x + 3 is 6, wouldnt all values of x make that inequality false (e / 2 < e / 6 is false for example)?

This is the page (example 4) for reference.

https://www.ocf.berkeley.edu/~yosenl/math/epsilon-...

1 Answer

Relevance
  • 5 years ago
    Favorite Answer

    Yes it is a mistake on the part of the example. The example should have proceeded as follows " the right hand side is at the *maximum* when x + 3 is at its *minimum*. Since the minimum of x + 3 is 4, we know that,

    |x - 2| < e / |x + 3| < e / 4

Still have questions? Get your answers by asking now.