$x={\left(\sqrt[3]{25}\cdot \sqrt{5}\right)}^{-1}={\left({25}^{\frac{1}{3}}\cdot 5^{\frac{1}{2}}\right)}^{-1}={\left({\left(5^2\right)}^{\frac{1}{3}}\cdot 5^{\frac{1}{2}}\right)}^{-1}={\left(5^{\frac{2}{3}}\cdot 5^{\frac{1}{2}}\right)}^{-1}=$      

$={\left(5^{\frac{2}{3}+\frac{1}{2}}\right)}^{-1}={\left(5^{\frac{4}{6}+\frac{3}{6}}\right)}^{-1}={\left(5^{\frac{7}{6}}\right)}^{-1}=5^{-\frac{7}{6}}$  

 

$y=\sqrt[6]{5}\cdot {625}^{\frac{1}{4}}=5^{\frac{1}{6}}\cdot {\left(5^4\right)}^{\frac{1}{4}}=5^{\frac{1}{6}}\cdot 5^1=5^{\frac{1}{6}+1}=5^{\frac{7}{6}}$  

 

Obliczmy iloczyn tych liczb:

$x\cdot y=5^{-\frac{7}{6}}\cdot 5^{\frac{7}{6}}=5^{-\frac{7}{6}+\frac{7}{6}}=5^0=1$  

 

Odp. B