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A question about the empty set 2018-06-17
From Andrey:
Hello there!
I got that an empty set is a subset of every set.
There is a question.
Is an empty set an element of every set?
∅ ⊆ {x}True
∅ ∈{x}?
Sorry if the question is easy. A set theory is a bit confusing.

Answered by Penny Nom.
A question in set theory 2015-02-25
From Jared:
If a set A={1,2,3} and set B={ {}, 1}

Can B be a subset of A? Since every Set contains an {} ?

Answered by Robert Dawson and Claude Tardif.
The empty set 2008-09-29
From wahab:
Why a null set is called a set? the definition of set includes that a set is a collection of well defined objects But a null set is having no value.
Answered by Harley Weston.
The empty set is a subset of every set 2006-11-14
From Narayana:
The empty set is a subset of every set
Answered by Stephen La Rocque and Penny Nom.
Sets and elements 2002-08-22
From Dianne:
I want to know why its okay to say that, for example, 6 is an element of the set of integers, but you get counted off for saying that the set of 6 is an element of the set of integers. How come?
Answered by Judi McDonald.
Composition of functions 2002-04-06
From Yvonne:
In our new text book, the following question occurs: State the domain and range of g(f(x))given that f(x) = -x2 - 4 and g(x) = sqrt(x)

The range of f(x), x<=-4, is the domain of g(x). BUT, there is no solution in the Real numbers for g(f(x))= sqrt(-x2 - 4).

In the solutions it says that this is not a function and therefore does not have a domain or range. Is it a relation? Is it anything?

Answered by Claude Tardif.



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