3] Calcule os valores das seguintes expressões: a) sqrt (49cdot 81)=underline ( ) b) sqrt [3](3)cdot sqrt [3](9)=underline ( ) c) sqrt (2)cdot sqrt (50)=underline ( ) d) sqrt ((25)/(16))=underline ( ) e) (sqrt (63))/(2cdot sqrt (7))=underline ( ) f) sqrt [3](3cdot 5^2)cdot sqrt [3](3^2cdot 5)=underline ( )

a) $\sqrt {49\cdot 81}=\sqrt {49}\cdot \sqrt {81}=7\cdot 9=63$<br /><br />b) $\sqrt [3]{3}\cdot \sqrt [3]{9}=\sqrt [3]{3\cdot 9}=\sqrt [3]{27}=3$<br /><br />c) $\sqrt {2}\cdot \sqrt {50}=\sqrt {2\cdot 50}=\sqrt {100}=10$<br /><br />d) $\sqrt {\frac {25}{16}}=\frac {\sqrt {25}}{\sqrt {16}}=\frac {5}{4}$<br /><br />e) $\frac {\sqrt {63}}{2\cdot \sqrt {7}}=\frac {\sqrt {9\cdot 7}}{2\cdot \sqrt {7}}=\frac {3\cdot \sqrt {7}}{2\cdot \sqrt {7}}=\frac {3}{2}$<br /><br />f) $\sqrt [3]{3\cdot 5^{2}}\cdot \sqrt [3]{3^{2}\cdot 5}=\sqrt [3]{3^{3}\cdot 5^{3}}=\sqrt [3]{3^{3}\cdot 5^{3}}=3\cdot 5=15$