Question

Let $A=\{1,2,3,4\},B=\{2,3,4,5,6\},$ then $A\Delta B=$

• A. $\{2,3,4\}$
• B. $\left\{1\right\}$
• C. $\{5,6\}$
• D. $\{1,5,6\}$

Answer 1

The correct option is D $\{1,5,6\}$

$A\Delta B=(A–B)\cup (B–A)$
$A-B=\{1,2,3,4\}-\{2,3,4,5,6\}=\left\{1\right\}$
$B-A=\{2,3,4,5,6\}-\{1,2,3,4\}=\{5,6\}$
$\Rightarrow A\Delta B=\left\{1\right\}\cup \{5,6\}=\{1,5,6\}$