2 votes 2 votes { 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 . Set Theory & Algebra set-theory&algebra discrete-mathematics engineering-mathematics set-theory + – ram_18051996 asked Jun 15, 2017 ram_18051996 513 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
5 votes 5 votes {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 :) junaid ahmad answered Jun 16, 2017 junaid ahmad comment Share Follow See all 5 Comments See all 5 5 Comments reply Show 2 previous comments ram_18051996 commented Jun 16, 2017 reply Follow Share 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 . 0 votes 0 votes junaid ahmad commented Jun 16, 2017 reply Follow Share Answer yourself these points tell which one is true or false. Remember subset is different from belongs to. 1 votes 1 votes ram_18051996 commented Jun 17, 2017 reply Follow Share 1. TRUE 2. FALSE 3. FALSE ok , i got it. 0 votes 0 votes Please log in or register to add a comment.