Q155 / 270 · NDA 2019 (Phase 1) · Mathematics

Consider the following statements for the two non-empty sets $A$ and $B$ : (1) $(\mathrm{A} \cap \mathrm{B}) \cup(\mathrm{A} \cap \overline{\mathrm{B}}) \cup(\overline{\mathrm{A}} \cap \mathrm{B})=\mathrm{A} \cap \mathrm{B}$ (2) $(\mathrm{A} \cup(\overline{\mathrm{A}} \cap \overline{\mathrm{B}}))=\mathrm{A} \cup \mathrm{B}$ Which of the above statements is/are correct ?

  • A
    1 only
  • B
    2 only
  • C
    Both 1 and 2
  • Correct answer
    D
    Neither 1 nor 2

Solution

1. $(A \cap B) \cup(A \cap \bar{B}) \cup(\bar{A} \cap B)=A \cup B$ Let us draw Venn diagram. Figure
$\therefore 1$ is correct. 2. $A \cup(\bar{A} \cap \bar{B})=A$Figure
$\therefore 2$ is not correct. Correct option (1).

Hence, the correct answer is option: 'D'.

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