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Se considera numerele rationale x=[tex] \frac{2}{7} [/tex] si y=[tex] \frac{5}{7} [/tex]. Calculati: A) [tex] y^{-1} [/tex] ; B) x+y;  C) x-y;  D)[tex] x^{2} [/tex].

Răspuns :

A)[tex]Yy ^{-1} = \frac{5}{7} * \frac{7}{5} =1[/tex]

B)[tex]x+y= \frac{2}{7} + \frac{5}{7}= \frac{7}{7} =1[/tex]

C)[tex]x-y= \frac{2}{7} - \frac{5}{7}=- \frac{3}{7} [/tex]

D)[tex] x^{2} = (\frac{2}{7} )^{2}=(\frac{2^{2}}{7^{2}} )=\frac{4}{49}[/tex]