What universal set(s) would you propose for each of the following?

(i) The set of right triangles, (ii) The set of isosceles triangles.

66. Let A = { 1, 2, { 3, 4 }, 5 }. Which of the following statements are incorrect and why?

Write down all the subsets of the following sets

(i) {a} (ii) {a, b} (iii) {1, 2, 3} (iv) φ

Given sets A = {1, 3, 5}, B = {2, 4, 6}, C = {0, 2, 4, 6, 8}, which of the following can be considered as universal set(s) of three sets A, B, C ?

(i) {0,1,2,3,4,5,6} (iii)ϕ

(iii) {0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10} (iv) {1, 2, 3, 4, 5, 6, 7, 8}

Write the following as intervals :

(i) {x : x ∈ R, – 4 < x ≤ 6} (ii) {x : x ∈ R, – 12 < x < –10} (iii) {x : x ∈ R, 0 ≤ x < 7} (iv) {x : x ∈ R, 3 ≤ x ≤ 4}

Write the following intervals in set-builder form :

(i)-∞ 31 (ii) (-∞, 0) (iii) [-1, ∞) (iv) (3, ∞)