NDA 2020 Maths · Mathematics · Sets, Relations and Functions · easy

For any sets A and B: 1. If A⊂ B, then A∪ B=B. 2. A-B=B-A always.

Single correct option

Consider the following statements for any sets

A

and

B

:
1. If

A\subset B

, then

A\cup B=B

.
2.

A-B=B-A

always.
Which of the statements is/are correct?

Show answer and solution

Answer: (A) 1 only

A\subset B

, every element of

A

is already in

B

, so

A\cup B=B

: statement 1 is true. For

A=\{1\}

B=\{2\}

we get

A-B=\{1\}\ne\{2\}=B-A

; the two differences are equal only when

A=B

. So statement 2 is false.

Original question written in the NDA 2020 Maths pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake