Răspuns :
a)
[tex] \sqrt{8} \div \sqrt{2} = \sqrt{8 \div 2} = \sqrt{4} = \sqrt{ {2}^{2} } = 2[/tex]
b)
[tex] \sqrt{15} \div \sqrt{5} = \sqrt{15 \div 5} = \sqrt{3} [/tex]
c)
[tex] \frac{ \sqrt{21} }{ \sqrt{5} } = \frac{ \sqrt{21} }{ \sqrt{5} } \times \frac{ \sqrt{5} }{ \sqrt{5} } = \frac{ \sqrt{21} \sqrt{5} }{ \sqrt{5 \sqrt{5} } } = \frac{ \sqrt{105} }{5} [/tex]
d)
[tex] \frac{ \sqrt{15} }{ \sqrt{14} } = \frac{ \sqrt{15} }{ \sqrt{14} } \times \frac{ \sqrt{14} }{ \sqrt{14} } = \frac{ \sqrt{15 \sqrt{14} } }{ \sqrt{14 \sqrt{14} } } = \frac{ \sqrt{210} }{14} [/tex]
e)
[tex] \frac{ \sqrt{27} }{ \sqrt{3} } = \frac{ \sqrt{3 \sqrt{9} } }{ \sqrt{3} } = \sqrt{9} = 3[/tex]
f)
[tex] \frac{ \sqrt{28} }{ \sqrt{21} } = \frac{ \sqrt{4} }{ \sqrt{3} } = \frac{2}{ \sqrt{ 3} } = \frac{2}{ \sqrt{3} } = \frac{2}{ \sqrt{3} } \times \frac{ { \sqrt{3} } }{ \sqrt{3} } = \frac{2 \sqrt{3} }{ \sqrt{3} \sqrt{3} } = \frac{2 \sqrt{3} }{3} [/tex]