Proof and Problem Solving - Sets Example 01

adampanagos.org
Given a set written using an elementhood test, we explicitly list all elements of the set between braces, {}. Several different examples are provided.
If you enjoyed my videos please "Like", "Subscribe", and visit adampanagos.org to setup your member account to get access to downloadable slides, Matlab code, an exam archive with solutions, and exclusive members-only videos. Thanks for watching!

[@twanapryce8176]

thank u

[@jeremyharris246]

Hi Adam, thanks for the videos, they're really helping me get to grips with this topic. Please would you explain why your last example does not go to infinity into the negative numbers, so that x is an element of {...,-2,-1,0,1,2}? It seems that if I follow the rules with x = -3, it follows the rules of 4 * -3 = -12 which is less than or equal to 8. Cheers

[@AdamPanagos]

Jeremy Harris Be careful. Note the absolute value sign. We need all values such that |4x| is less than or equal to 8. So, if x is -3, |4x| is 12 and thus not part of the final set. Hope that helps.

[@jeremyharris246]

Great explanation, thank you. I'll be more wary of simplifying the absolute value sign :)

[@AdamPanagos]

No worries, glad you got it!

[@cranexe9035]

Hello, at 0:56, you say that 0 is an element of natural numbers, which is not correct. N is a subset of W (Whole nos) that contain 0 too. But N={1,2,3...} and not W={0,1,2,3...}.

[@Alphabunsquad]

Not necessarily. There is disagreement about that topic. Whole numbers can also refer to Integers. Some people have N include 0 and use counting numbers to refer to N excluding 1