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# If A={3,6,9,12,15,18,21},B={4,8,12,16,20},C={2,4,6,8,10,12,14,16},D={5,10,15,20} (i) A-B

$\begin{array}{1 1}(A)\;\{3,6,9,12,15,18,21\}&(B)\;\{3,6,9,15,18,21\}\\(C)\;\{4,8,12,16,60\}&(D)\;\phi\end{array}$

Can you answer this question?

$A={3,6,9,12,15,18,21},B={4,8,12,16,20}$
Here only element 12 of set A is common to set B.
$\therefore$ Difference of sets
$\Rightarrow A-B=\{3,6,9,12,15,18,21\}-\{4,8,12,16,20\}$
$\Rightarrow \{3,6,9,15,18,21\}$
Hence (B) is the correct answer.
answered May 27, 2014