Explicație pas cu pas:
[tex]a) \frac{9}{4} + \frac{3}{2} = \frac{9}{4} + \frac{3 \times 2}{2 \times 2} = \frac{9}{4} + \frac{6}{4} = \frac{9 + 6}{4} = \frac{15}{4} = 3 \frac{3}{4} [/tex]
[tex]b) \frac{5}{6} - \frac{4}{3} = \frac{5}{6} - \frac{4 \times 2}{3 \times 2} = \frac{5}{6} - \frac{8}{6} = \frac{5 - 8}{6} = - \frac{3}{6} ^{(2} = - \frac{1}{2} [/tex]
[tex]c) \frac{7}{6} + \frac{5}{4} = \frac{7 \times 2}{6 \times 2} + \frac{5 \times 3}{4 \times 3} = \frac{14}{12} + \frac{15}{12} = \frac{14 + 15}{12} = \frac{29}{12} = 2 \frac{5}{12} [/tex]
[tex]d) \frac{7}{4} - \frac{8}{5} = \frac{7 \times 5}{4 \times 5} - \frac{8 \times 4}{5 \times 4} = \frac{35}{20} - \frac{32}{20} = \frac{35 - 32}{20} = \frac{3}{20} [/tex]
[tex]e)2 \frac{3}{8} + ( - \frac{13}{6}) = \frac{19}{8} + ( - \frac{13}{6}) = \frac{19 \times 3}{8 \times 3} + \frac{( - 13) \times 4}{6 \times 4} = \frac{57}{24} + ( - \frac{52}{24}) = \frac{57 + ( - 52)}{24} = \frac{5}{24} [/tex]
[tex]f)( - \frac{7}{4}) - 1 \frac{3}{14} = - \frac{7}{4} - \frac{17}{14} = \frac{ - 7 \times 7}{4 \times 7} - \frac{17 \times 2}{14 \times 2} = - \frac{49}{28} - \frac{34}{28} = \frac{ - 49 - 34}{28} = - \frac{83}{28} = - 2 \frac{27}{28} [/tex]
[tex]g)( - \frac{11}{12}) - 1 \frac{4}{9} = - \frac{11}{12} - \frac{13}{9} = \frac{ - 11 \times 3}{12 \times 3} - \frac{13 \times 4}{9 \times 4} = - \frac{33}{36} - \frac{52}{36} = \frac{ - 33 - 52}{36} = - \frac{85}{36} = - 2 \frac{13}{36} [/tex]
[tex]h)( - 2 \frac{1}{8}) + \frac{9}{10} = - \frac{17}{8} + \frac{9}{10} = \frac{ - 17 \times 5}{8 \times 5} + \frac{9 \times 4}{10 \times 4} = - \frac{85}{40} + \frac{36}{40} = \frac{ - 85 + 36}{40} = - \frac{49}{40} = - 1 \frac{9}{40} [/tex]
