Submitted by Tharsis101 t3_10nn59i in explainlikeimfive
Ellykos t1_j6bvvnz wrote
Reply to comment by Ogg8474 in ELI5: Why do imaginary numbers even need to exist? by Tharsis101
If you didn't know, Z, Q and R are also used. Z are for the integers (-inf to +inf) while N are the natural numbers (0 to +inf). Q is for the rationnal numbers, all the numbers that can be written as a quotient a/b where b isn't equal to 0 (you also have Q' for the irrationnals like pi). Finally R are for the reals. It's important to note that each categorie can contain some of the other categories. For example, all natural numbers are integers, and all integers are real.
EDIT : As commented below, apparently 0 isn't included in N, but in N* (Natural numbers including 0) or W (Whole numbers). Didn't learn it that way, but maybe some people did ?
The_camperdave t1_j6c57zf wrote
> while N are the natural numbers (0 to +inf)
I was taught that Natural numbers were 1,2,3,..., and Whole numbers were 0,1,2,3...
Ellykos t1_j6c6rvv wrote
Looking online I can see that W is used for the Whole numbers, but I never saw the W symbol used in all my math classes.
Personally I learned that 0 was a natural number and looking online it is said that 0 was not included in the original definition, but was later added. To avoid mistake, N* is often used to indicate that it contains 0. At the end, it's not really that important but it's good to know !
[deleted] t1_j6c0vsv wrote
[deleted]
Ellykos t1_j6c17rj wrote
> integrating by parts
I guess it's a calculus class ? Good luck with that, it was dreadful for me; I had to do the class 3 times before passing the class lol
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