Chapter 1: Sets

Exercise

Question

Question: 3 (iv)

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Taking the set of natural numbers as the universal set, write down the complements of the following sets:

(iv) {x : x is a prime number}

Answer

1
Find the complement of the given set by finding the elements of the universal set of numbers that are not elements of the given set.
Answer: {x : x $∈$ N, x is a composite number or x = 1} {itip:Interesting Fact|The number 1 is neither prime nor composite. It has only one factor, whereas a prime number has exactly two factors and a composite number has more than two factors.}
Reason: Natural numbers consist of prime{math_tip:def_prime_number} numbers, composite{math_tip:def_composite_number} numbers, and 1. Therefore, after removing the prime numbers, only composite numbers and 1 remain.
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