[tex]3 \times \frac{1}{2} = \frac{3 \times 2 + 1}{2} = \frac{7}{2} \\ 1 \times \frac{2}{3} = \frac{5}{2} \\ 1 \times \frac{3}{4} = \frac{7}{4} \\ = > \frac{7}{2} + \frac{5}{2} + \frac{7}{4} \\ aducem \: la \: numitorul \: comun \\ care \: este \: 4 \\ \frac{14}{4} + \frac{10}{4} + \frac{7}{4} = \frac{31}{4} [/tex]
Sper ca se vede
