The symmetric difference of A = {1, 2, 3} and B = {3, 4, 5} is
(a) \(\{1,2\}\)
(b) \(\{1,2,4,5\}\)
(c) \(\{4,3\}\)
(d) \(\{2,5,1,4,3\}\)
Solution
\[ A=\{1,2,3\}, \qquad B=\{3,4,5\} \]
\[ A-B=\{1,2\} \]
\[ B-A=\{4,5\} \]
Symmetric difference:
\[ A\Delta B=(A-B)\cup(B-A) \]
\[ =\{1,2\}\cup\{4,5\} \]
\[ =\{1,2,4,5\} \]
Answer
\[ \boxed{\{1,2,4,5\}} \]
Correct option: (b)
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