Question

A = { x : 6 < x < 10} and B = { x : 0 < x < 15}. Find B - A.

• A. {7, 8, 9}
• B. {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14}
• C. {1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14}
• D. {}

Answer 1

The correct option is C {1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14}

Given :
A = { x : 6 < x < 10} = {7, 8, 9}
B = { x : 0 < x < 15} = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14}
B - A consists of elements from B which are present only in B and not A.
i.e. B - A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14} - {7, 8, 9} = {1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14}

$\therefore$ B - A = {1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14}