Răspuns:
D. 4
Explicație pas cu pas:
[tex]\frac{a}{\sqrt{2} } = \frac{\sqrt{8} }{b} \\a*b=\sqrt{2}* \sqrt{8} =\sqrt{2*8} =\sqrt{16} =4\\[/tex]
[tex]\frac{\sqrt{3}*c }{\sqrt{15} } = \frac{1}{\sqrt{5}*d } \\\\({\sqrt{3}*c)*(\sqrt{5}*d)=\sqrt{15} *1\\[/tex]
[tex](\sqrt{3} *\sqrt{5}) *c*d=\sqrt{15} \\\\\sqrt{15}*c*d=\sqrt{15}[/tex]
[tex]c*d=\frac{\sqrt{15} }{\sqrt{15} } =1\\\\a*b*c*d=(a*b)*(c*d)=4*1=4[/tex]
