a)
\sqrt{196*25}=\sqrt{(14*5)^2}=\sqrt{70^2}=70
\sqrt{36*121}=\sqrt{(6*11)^2}=\sqrt{66^2}=66
\sqrt{169*9}=\sqrt{(13*3)^2}=\sqrt{39^2}=39
\sqrt{144*49}=\sqrt{(12*7)^2}=\sqrt{84^2}=84
\sqrt{81*225}=\sqrt{(9*15)^2}=\sqrt{135^2}=135
b)
\sqrt[3]{8*125}=\sqrt[3]{1000}=\sqrt[3]{10^3}=10
\sqrt[3]{27*1000}=\sqrt[3]{(3*10)^3}=\sqrt[3]{30^3}=30
\sqrt[3]{-64*216}=-\sqrt[3]{(4*6)^3}=-\sqrt[3]{24^3}=-24
\sqrt[3]{125 * (-343)}=-\sqrt[3]{(5*7)^3}=-\sqrt[3]{35^3}=-35
\sqrt[3]{-8 * (-729)}=-\sqrt[3]{2^3*(-9)^3}=\sqrt[3]{18^3}=18