Question
Sat April 18, 2015 By: Abhishek Kumar

why do we write x:x in in set builder form?

Expert Reply
Vimala Ramamurthy
Sun April 19, 2015
I n space s e t space b u i l d e r space f o r m comma space a space s e t space i s space d e s c r i b e d space b y space a space c h a r a c t e r i z i n g space p r o p e r t y space o f space i t s space e l e m e n t s. S u p p o s e space A space i s space a space s e t space a n d space w e space a r e space d e f i n i n g space i t space a s space e v e n space n a t u r a l space n u m b e r s. T h e n space A space c a n space b e space w r i t t e n space i n space R o s t e r space f o r m space a s comma A equals open curly brackets 2 comma 4 comma 6 comma 8 comma 10 comma 12 comma... close curly brackets L e t space u s space w r i t e space A space i n space s e t space b u i l d e r space f o r m. L e t space x space b e space a space n a t u r a l space n u m b e r. T h e n space 2 cross times x space i s space a n space e l e m e n t space o f space t h e space s e t. therefore A equals open curly brackets x colon x element of N comma x equals 2 n comma space n element of N close curly brackets T h e r e f o r e comma space w e space a r e space d e s r i b i n g space t h e space p r o p e r t y space i n space t h e space s e t space b u i l d e r space f o r m.
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