Set theory

Question

{ a } ∈ A 

but

a ∉ A

why ?

here  ' a is the element of set {a} ' ,and  ' set {a} is the element of A" , so " a also element of A  " . please clear my doubt .

Answer 1

{a} ∈ A means {a} must be present as element in set A.

whereas,a ∈ A means only a must be present as element in A

Example:let A={ {a},b,c,{b,c}} then {a} ∈ A is correct but a ∈ A is NOT.

and let B={a,b,{c,d}} then a ∈ B is correct but {a} ∈ B is not.

HOPE IT WILL BE CLEAR NOW :)

Comments

let S is a SET of all classes in a school.

and C is a CLASS in this school

than if a student who is member of this class C and class C is member of S

than  this student also member of this school.

i am very confuse . Please clear my doubt .

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Answer yourself these points tell which one is true or false.

Remember subset is different from belongs to.

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1.   TRUE

2.   FALSE

3.   FALSE

ok , i got it.