a) [tex] \sqrt{( \sqrt{14} ) ^{2} *( \sqrt{56} ) ^{2}}= \sqrt{14*56} = \sqrt{2*7*7*2 ^{3} } =7*4=28[/tex]
b) [tex] \sqrt{(13- \sqrt{69} ) ^{2} * (13+ \sqrt{69}) ^{2} } = \sqrt{(13 ^{2} -69) ^{2} } =13 ^{2} -69=169-69[/tex]
c) [tex] \sqrt{ (\frac{10 \sqrt{2}- \sqrt{7}}{8} ) ^{2} *( \frac{ \sqrt{200} + \sqrt{7} }{2} ) ^{2} } =[/tex]
[tex] \sqrt{ \frac{(200- 7)^{2}}{8^{2}*2^{2}} } =\frac{193}{8*2} [/tex]