Question

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

Answer 1

A)$Yy ^{-1} = \frac{5}{7} * \frac{7}{5} =1$

B)$x+y= \frac{2}{7} + \frac{5}{7}= \frac{7}{7} =1$

C)$x-y= \frac{2}{7} - \frac{5}{7}=- \frac{3}{7}$

D)$x^{2} = (\frac{2}{7} )^{2}=(\frac{2^{2}}{7^{2}} )=\frac{4}{49}$