Question

2 radical din 7 ori 2 radical din 3 = ?

Answer 1

$2 \sqrt{7} \cdot2 \sqrt{3} =2( \sqrt{7} \cdot \sqrt{3} )=2 \sqrt{21} = \sqrt{2^2 \cdot 21} = \sqrt{4 \cdot 21} =\boxed{ \sqrt{84} }.$