Question

If u = {set of natural numbers less than 20), A = factors of 18), and B = {odd numbers less than 15), then find (ii) A' U B' (1) (A n B)'​

Answer 1

Answer:

Which is the sum of odd numbers beginning with 1?

The total of any set of sequential odd numbers beginning with 1 is always equal to the square of the number of digits, added together. If 1,3,5,7,9,11,…, (2n-1) are the odd numbers, then; Sum of first odd number = 1. Sum of first two odd numbers = 1 + 3 = 4 (4 = 2 x 2). Sum of first three odd numbers = 1 + 3 + 5 = 9 (9 = 3 x 3).

Answer 2

Answer:

Given, universal set, U={1,2,3,4,5,6,7}

A={1,2,5,7}

B={3,4,5,6}

(A∪B) ′

=U−(A∪B)

={1,2,3,4,5,6,7}−{1,2,3,4,5,6,7}

=ϕA ′ ∩B ′

=(U−A)n(U−B)

={3,4,6}n{1,2,7}

=ϕ

Hence (A∪B) ′

=A ′ ∩B ′

.