Răspuns:
a) 58/27; b) -5/16; c) -16/45
Explicație pas cu pas:
a)
[tex] - \frac{20}{27} + \frac{5}{9} - \frac{2}{3} + 3 = \frac{ - 20 + 5 \times 3 - 2 \times 9 + 3 \times 27}{27} \\ = \frac{ - 20 + 15 - 18 + 81}{27} = \frac{96 - 38}{27} = \frac{58}{27} [/tex]
b)
[tex] - \frac{1}{6} - \frac{15}{8} + \frac{31}{48} + \frac{13}{12} \\ = \frac{ - 1 \times 8 - 15 \times 6 + 31 + 13 \times 4}{48} \\ = \frac{ - 8 - 90 + 31 + 52}{48} \\ = \frac{83 - 98}{48} = \frac{ - 15}{48} = - \frac{5}{16} [/tex]
c)
[tex] - \frac{7}{9} + \frac{2}{5} + \frac{1}{15} - \frac{2}{45} \\ = \frac{ - 7 \times 5 + 2 \times 9 + 1 \times 3 - 2}{45} \\ = \frac{ - 35 + 18 + 3 - 2}{45} = \frac{21 - 37}{45} = - \frac{16}{45} [/tex]
