Calculati : 1 pe 2 + 5 pe 7
3 pe 4 + 6 pe 11
5 pe 3+ 4 pe 9
1 pe 2 +1 pe 3 +1 pe 6
2 pe 5 +3 pe 2 +7pe 10
4 pe 9 + 1 pe 3 + 7 pe 18
1 pe 2 +1 pe 3 +1 pe 4+1pe 5
1 pe 40 + 3 pe 8+7pe 4+ 1 pe 2
1 pe 9 +2pe 18+3 pe 27+4 pe 36 ...
Explicat !! Dau cel mai bun raspuns si puncte !! Urgentt!!

[tex]a) \frac{1}{2} + \frac{5}{7} = \frac{1 \times 7}{2 \times 7} + \frac{5 \times 2}{7 \times 2} = \frac{7}{14} + \frac{10}{14} = \frac{7 + 10}{14} = \frac{17}{14} = 1 \frac{3}{14} [/tex]

[tex]b) \frac{3}{4} + \frac{6}{11} = \frac{3 \times 11}{4 \times 11} + \frac{6 \times 4}{11 \times 4} = \frac{33}{44} + \frac{24}{44} = \frac{33 + 24}{44} = \frac{57}{44} = 1 \frac{13}{44} [/tex]

[tex]c) \frac{1}{2} + \frac{1}{3} + \frac{1}{6} = \frac{1 \times 3}{2 \times 3} + \frac{1 \times 2}{3 \times 2} + \frac{1}{6} = \frac{3}{6} + \frac{2}{6} + \frac{1}{6} = \frac{3 + 2 + 1}{6} = \frac{6}{6} = 1 [/tex]

[tex]d) \frac{2}{5} + \frac{3}{2} + \frac{7}{10} = \frac{2 \times 2}{5 \times 2} + \frac{3 \times 5}{2 \times 5} + \frac{7}{10} = \frac{4}{10} + \frac{15}{10} + \frac{7}{10} = \frac{4 + 15 + 7}{10} = \frac{26}{10} = \frac{13}{5} = 2 \frac{3}{5} [/tex]

[tex]e) \frac{4}{9} + \frac{1}{3} + \frac{7}{18} = \frac{4 \times 2}{9 \times 2} + \frac{1 \times 6}{3 \times 6} + \frac{7}{18} = \frac{8}{18} + \frac{6}{18} + \frac{7}{18} = \frac{8 + 6 + 7}{18} = \frac{21}{18} = \frac{7}{6} = 1 \frac{1}{6} [/tex]

[tex]f) \frac{5}{3} + \frac{4}{9} = \frac{5 \times 3}{3 \times 3} + \frac{4}{9} = \frac{15}{9} + \frac{4}{9} = \frac{15 + 4}{9} = \frac{19}{9} = 2 \frac{1}{9} [/tex]

[tex]g) \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} = \frac{1 \times 30}{2 \times 30} + \frac{1 \times 20}{3 \times 20} + \frac{1 \times 15}{4 \times 15} + \frac{1 \times 12}{5 \times 12} = \frac{30}{60} + \frac{20}{60} + \frac{15}{60} + \frac{12}{60} = \frac{30 + 20 + 15 + 12}{60} = \frac{77}{60} = 1 \frac{17}{60} [/tex]

[tex]h) \frac{1}{40} + \frac{3}{8} + \frac{7}{4} + \frac{1}{2} = \frac{1}{40} + \frac{3 \times 5}{8 \times 5} + \frac{7 \times 10}{4 \times 10} + \frac{1 \times 20}{2 \times 20} = \frac{1}{40} + \frac{15}{40} + \frac{70}{40} + \frac{20}{40} = \frac{1 + 15 + 70 + 20}{40} = \frac{106}{40} = \frac{53}{20} = 2 \frac{13}{20} [/tex]

[tex]i) \frac{1}{9} + \frac{2}{18} + \frac{3}{27} + \frac{4}{36} = \frac{1}{9} + \frac{1}{9} + \frac{1}{9} + \frac{1}{9} = \frac{1 + 1 + 1 + 1}{9} = \frac{4}{9} [/tex]