Question

EXERCISE 7 B 1. Write each of the following sets in Roster form and write (i) A = (x :* € W.* ​

Answer 1

Answer:

(i) Given: D = {t | t3 = t, t ∈ R}

To find: Roster form of given set

t3 = t

⇒ t3 – t = 0

⇒ t(t2 – 1) = 0

⇒ t(t – 1)(t + 1) = 0

⇒ t = 0, -1 or 1

So, D = {-1, 0, 1}

(ii) Given:

To find: Roster form of given set

⇒ w – 2 = 3(w + 3)

⇒ w – 2 = 3w + 9

⇒ 3w – w = - 9 – 2

⇒ 2w = –11

(iii) Given: F = {x | x4 – 5x2 + 6 = 0, x ∈ R}

To find: Roster form of given set

x4 – 5x2 + 6 = 0

⇒ x4 – 3x2 – 2x2 + 6 = 0

⇒ x2(x2 – 3) – 2(x2 – 3) = 0

⇒ (x2 – 3) (x2 – 2) = 0

⇒ x2 = 3 or 2

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