State which of the following statement are true and which ones are false . Justify your answer .
(i) `21 in {x|x ` has exactly four positive factors }
(ii) `64 in {y| ` the sun of the all the positve factors of y is 2y }
(iii) `2 in { x |x^4- 3x^3+4x^2-5x+6=0}`
(iv) 23562 `in {y|y ` is divisible by 9}

Explanation

Let's analyze each statement step by step to determine whether they are true or false, providing justifications for each conclusion.

### Statement (i): `21 in {x | x has exactly four positive factors}`
1. **Identify the positive factors of 21**:
- The positive factors of 21 are 1, 3, 7, and 21.
2. **Count the number of positive factors**:
- The total number of positive factors is 4.
3. **Conclusion**:
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