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# Please explain in a different way

Posted on 2011-10-19

PLEASE EXPLAIN IT IN A DIFFERENT WAY

Define a set X of numbers as follows

B. 2 belongs X.

R1. If x belongs to X, so is 10x

R2. If x belongs X, so is x+4

a. List all the elements of X that are less than 30.

b. Explain why there are no odd numbers in X.

Answer

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2 belongs to X

x belongs to X ==> 10x belongs to X

x belongs to X==>x+4 belongs to x

Find all of X belongs to 30

2 2 20

20 6 24

6 10 28

24 14

18

22

26

odds not belongs to x

4 not belongs to x

8 not belongs to x

12 not belongs to x

16 not belongs to x