oblicz sumę oraz iloczyn liczb x i y : b) x=[latex]sqrt{}frac{28}{63}, y= sqrt{}frac{75}{48} c) x= sqrt[3]{}frac{1}{125}, y= sqrt[3]{3}frac{3}{8} d) x= sqrt[3]{-8} , y= sqrt[3]{}frac{-270}{-640}[/latex]

[latex]b)\ x=sqrtfrac{28}{63}=sqrtfrac{4cdot7}{9cdot7}=sqrtfrac49=frac23\ y=sqrtfrac{75}{48}=sqrtfrac{25cdot3}{16cdot3}=sqrtfrac{25}{16}=frac54\ \ x+y=frac23+frac54=frac{8}{12}+frac{15}{12}=frac{23}{12}=1frac{11}{12}\ x-y=frac23-frac54=frac{8}{12}-frac{15}{12}=frac{-7}{12}=-frac{7}{12}\ \ \ [/latex]   [latex]c)\ x=sqrt[3]{frac{1}{125}}=frac15\ y=sqrt[3]{3frac{3}{8}}=sqrt[3]{frac{27}{8}}=frac32\ \ x+y=frac15+frac32=frac{2}{10}+frac{15}{10}=frac{17}{10}=1frac{7}{10}\ x-y=frac15-frac32=frac{2}{10}-frac{15}{10}=frac{-13}{10}=-1frac{3}{10}\ \ \[/latex]   [latex]d)\ x=sqrt[3]{-8}=-2\ y=sqrt[3]{frac{-270}{-640}}=sqrt[3]{frac{-3^3cdot10}{-4^3cdot10}}=sqrt[3]{(frac34)^3}=frac34\ \ x+y=-2+frac34=-1frac14\ x-y=-2-frac34=-2frac34[/latex]