Finite and Infinite Sets

[@16botchock]

Man, you helped me like a lot. As a 7th grader, I don't know this. I have a test tomorrow and this helps me like a lot. Thank you :)

[@Greenemath]

Glad it helped!

[@zavianndunbar8228]

Fi real

[@sherry6296]

Bro it’s the first day of school and you already saved me ty

[@Greenemath]

Glad it was helpful.

[@tamikah4258]

Is the set of all months with 33days infinity or finity?

[@Greenemath]

empty, no months have 33 days. The set has no elements.

[@Kay-vw9sf]

I have a question I still don’t understand in my class, so the question is “is the set B= {all numbers of the form 4n+4, for n a natural number} closed under multiplication ?” What exactly are we multiplying?

[@Greenemath]

If n is a natural number, it just means the numbers {1, 2, 3, 4, 5, 6, 7,...} All you have to do here is plug in a few natural numbers and establish a pattern. The first natural number is 1, so just plug in for n: 4(1) + 4 = 8 Then the second natural number is 2: 4(2) + 4 = 12 Next, we do 3 and we see the pattern: 4(3) + 4 = 16 Each time we are increasing by 4, so this gives us a set: B = {8, 12, 16, 20, 24,...}

[@Kay-vw9sf]

GreeneMath.com ohh okay thank you so much!

[@Greenemath]

@@Kay-vw9sf You are very welcome! :)

[@faithjoycasona1229]

Is this finite or infinite? {0} please reply plsss this is for my class

[@Greenemath]

A infinite set has an unlimited number of elements, whereas a finite set has a countable number. In your example, the set has one element, the number zero. This is a finite set.

[@lauramckinney5365]

Thank you

[@Greenemath]

You're welcome

[@stevesealey6132]

Thank u 😁😁

[@Greenemath]

You're welcome!

[@md1024tt]

Very helpful for my tests THANK YOU VERY MUCH

[@Greenemath]

You're welcome, good luck on your test.

[@zeus1101]

If 1,2,3...7 is it finite?

[@Greenemath]

It's not really in set notation, but if those were the only members of the set, then yes. I finite set has a limited number of elements.

[@zeus1101]

Thanks

[@1law._leve]

You help me to do my test

[@Greenemath]

That's awesome, hope you did well! :)

[@1law._leve]

@@Greenemath I got A

[@Greenemath]

@@1law._leve I'm so glad to hear that! :)

[@jhernellepatilan3623]

Thx

[@Greenemath]

You are very welcome :)

[@kylegelicame979]

{..., -3, -2, -1, 0, 1, 2,} Is it finite or infinite

[@Greenemath]

Why is there a comma after the 2? Is it supposed to be the set of integers? {...,-3,-2,-1,0,1,2,...} like that? It's an infinite set, it will continue in both directions forever.

[@kylegelicame979]

No its {..., -3, -2, -1, 0, 1, 2} sorry for my mistake

[@Greenemath]

@@kylegelicame979 It's still infinite because of the left side ellipses. This tells you that going to the left you keep decreasing by 1 forever. So before -3, you have -4, and then -5, and so on and so forth. If a set has an uncountable number of elements it's infinite. If a set has a countable number, it's finite. Now there are finite sets that are huge, but as long as it's some countable number, it's finite.

[@kylegelicame979]

@@Greenemath thanks for the help

[@Greenemath]

@@kylegelicame979 You are very welcome! :)

[@majeralc8106]

I really didn't get the proper subset. H={1,5} D={9,1,7,5} Is that a proper subset? How about this A={1,8,4,2,6} K={8,4,3,7,9} Please reply 😭 I didn't get it 😭😭😭

[@Greenemath]

Proper subset just means you have a subset and they are not equal to each other. First case: H = {1, 5} D = {1, 5, 7, 9} H is a proper subset of D. D contains all of the elements of H and D and H are not equal. Second case: A = {1, 2, 4, 6, 8} K = {3, 4, 7, 8, 9} These two sets are not equal and also neither is going to be a subset. A contains elements not in K and K contains elements not in A.

[@majeralc8106]

@@Greenemath Thank you so much 😭🙏

[@jengathecat8667]

thanks dude

[@Greenemath]

No problem! Thank you for watching :)

[@adriannedumahel8937]

Thanks

[@Greenemath]

You are very welcome! :)