Find the union of each of the following pairs of sets :
(i) X = {1, 3, 5} Y = {1, 2, 3}
(ii) A = [ a, e, i, o, u} B = {a, b, c}
(iii) A = {x : x is a natural number and multiple of 3} B = {x : x is a natural number less than 6}
(iv) A = {x : x is a natural number and 1 < x ≤ 6 } B = {x : x is a natural number and 6 < x < 10 }
(v) A = {1, 2, 3}, B = φ

Solution:

The "union" of two sets is one of the operations on sets and it results in a set that contains the elements of both sets by removing duplicates if any.

Thus,

(i) When X = {1, 3, 5} and Y = {1, 2, 3},

 X υ Y = {1, 2, 3, 5}

(ii) When  A = {a, e, i, o, u} and B = {a, b, c},

 A υ B = {a , b, c, e, i, o, u}

(iii) A = { x : x is a natural number and multiple of 3} = {3, 6, 9....}

B = { x : x is a natural number less than 6} = {1, 2, 3, 4, 5}

Then A υ B = {1, 2, 4, 5, 3, 6, 9, 12....}

Therefore, A υ B = {x : x = 1, 2, 4, 5 or a multiple of 3}

(iv) A = { x : x is a natural number and 1 < x ≤ 6 } = {2, 3, 4, 5, 6}

B = { x : x is a natural number and 6 < x < 10 } = {7, 8, 9}

Then A υ B = {2, 3, 4, 5, 6, 7, 8, 9}

Therefore,

A υ B = {x : x ∈ N and 1 < x < 10}

(v) When A = {1, 2, 3} and  B = Φ, 

A υ B = {1, 2, 3}

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NCERT Solutions Class 11 Maths Chapter 1 Exercise 1.4 Question 1

Find the union of each of the following pairs of sets : (i) X = {1, 3, 5} Y = {1, 2, 3} (ii) A = [ a, e, i, o, u} B = {a, b, c} (iii) A = {x : x is a natural number and multiple of 3} B = {x : x is a natural number less than 6} (iv) A = {x : x is a natural number and 1 < x ≤6 } B = {x : x is a natural number and 6 < x < 10 } (v) A = {1, 2, 3}, B = φ

Summary:

We are asked to find the union of each of the following pairs of sets. We found that
(i) When X = {1, 3, 5} Y = {1, 2, 3}, X υ Y = {1, 2, 3, 5}
(ii) When A = [ a, e, i, o, u} B = {a, b, c}, A υ B = {a , b, c, e, i, o, u}
(iii) When A = {x : x is a natural number and multiple of 3} B = {x : x is a natural number less than 6}, A υ B = {x : x = 1, 2, 4, 5 or a multiple of 3}
(iv) When A = {x : x is a natural number and 1 < x ≤ 6 } B = {x : x is a natural number and 6 < x < 10 }, A υ B = {2, 3, 4, 5, 6, 7, 8, 9}
(v) When A = {1, 2, 3}, B = φ, A υ B = {1, 2, 3}