Chapter 1: Sets

Exercise

Question

Question: 3 (xi)

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

(xi) {x : x ∈ N and 2x + 1 > 10}

Answer

1
Simplify the inequality (2x + 1 > 10) by moving the constants to one side.
2x > 10 - 1
2x > 9
2
Find the elements of the set by solving the inequality from Step 1.
x > 9 / 2
Therefore, Set = {x : x $∈$ N, x > 9 / 2}
3
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 $≤$ (9 / 2)} or {1, 2, 3, 4}
Reason: The set contains all natural numbers that are greater than 9 / 2. Therefore, its complement consists of all natural numbers that are less than or equal to 9 / 2.
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