NCERT Class XI Mathematics - Sets - Solutions
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Question : 31
Total: 73
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
(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:
(i) Here X = {1, 3, 5} and Y = {1, 2, 3}
∴ X ∪ Y = {1, 2, 3, 5}
(ii) Here A = {a, e, i, o, u} and B = {a, b, c}
∴ A ∪ B = {a, b, c, e, i, o, u}
(iii) Here A = {x: x is a natural number and multiple of 3} = {3, 6, 9, 12, ......} and B = {x: x is a natural number less than 6} = {1, 2, 3, 4, 5}
∴ A ∪ B = {1, 2, 3, 4, 5, 6, 9, 12, 15, .....}
(iv) Here A = {x: x is a natural number and 1 < x ≤ 6} = {2, 3, 4, 5, 6} and B = {x: x is a natural number and 6 < x < 10} = {7, 8, 9}
∴ A ∪ B = {2, 3, 4, 5, 6, 7, 8, 9}
(v) Here A = {1, 2, 3} and B = ϕ
∴ A ∪ B = {1, 2, 3}.
∴ X ∪ Y = {1, 2, 3, 5}
(ii) Here A = {a, e, i, o, u} and B = {a, b, c}
∴ A ∪ B = {a, b, c, e, i, o, u}
(iii) Here A = {x: x is a natural number and multiple of 3} = {3, 6, 9, 12, ......} and B = {x: x is a natural number less than 6} = {1, 2, 3, 4, 5}
∴ A ∪ B = {1, 2, 3, 4, 5, 6, 9, 12, 15, .....}
(iv) Here A = {x: x is a natural number and 1 < x ≤ 6} = {2, 3, 4, 5, 6} and B = {x: x is a natural number and 6 < x < 10} = {7, 8, 9}
∴ A ∪ B = {2, 3, 4, 5, 6, 7, 8, 9}
(v) Here A = {1, 2, 3} and B = ϕ
∴ A ∪ B = {1, 2, 3}.
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