15. Write the following sets in the roster form :

E = The set of all letters in the word TRIGONOMETRY

 If A ⊆ B, show that:

(a) A ∩ B=A (b) A ∪ B = B

Write the following intervals in set-builder form :

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

Write the following sets in the roster form :

(i) A = {jt : x ∊ Z and x is a root of the quadratic equation x² - 3x - 10 = 0}

(ii) B = {x : x ∊ N, -5 < x - 2 < 5}

(iii) C = {x : jc is an odd prime number less than 30}