7. 6√8 = √6*6*8 = √2887
A. 3√12 = √108
B. 12√2 = √288
C. 10√3 = √300
D. 8√6 = √384
Odp: A
8. [tex]16^{15} +8^{20}+4^{30}+2^{60} =(2^{4}) ^{15} +(2^{3}) ^{20}+(2^{2} )^{30}+2^{60} =\\2 ^{60} +2 ^{60}+2^{60}+2^{60} = 4*2^{60}=2^{2} *2^{60}=2^{62}[/tex]
9. a)[tex]\frac{4^{5} *5^{3} }{20^{4} } =\frac{4^{5} *5^{3} }{5^{4} *4^{4} } =\frac{4 }{5 }[/tex]
b)[tex]\frac{2^{9} }{81} *\frac{3^{7} }{4^{5} }=\frac{2^{9} }{3^{4} } *\frac{3^{7} }{(2^{2}) ^{5} }=\\\frac{2^{9} }{3^{4} } *\frac{3^{7} }{2^{10}}=\frac{3^{3} }{2 } =\frac{27}{2}[/tex]
10. a)[tex]\sqrt{25*3+25*8+25*5} = \sqrt{25(3+8+5)} =\\\sqrt{25*16} =\sqrt{400} =20[/tex]
b) [tex]\sqrt[3]{343+343*38-343*12} =\sqrt[3]{343(1+38-12)} =\\\sqrt[3]{343*27}=\sqrt[3]{9261}=21[/tex]
