Question

Thực hiện phép tính:

4, 2/7+ 1/9+ 3/7+ 5/9+ -5/6

5, -5/7+ 3/4+ -1/5+ -2/7+ 1/4

6, -3/31+ -6/17+ 1/25+ -28/31+ -1/17+ -1/5 

Answer 1

4: \(=\dfrac{2+3}{7}+\dfrac{1+6}{9}-\dfrac{5}{6}=\dfrac{5}{7}+\dfrac{7}{9}-\dfrac{5}{6}=\dfrac{83}{126}\)

5: \(=\dfrac{-5-2}{7}+\dfrac{3+1}{4}-\dfrac{1}{5}=-\dfrac{1}{5}\)

6: \(=\dfrac{-3-28}{31}+\dfrac{-6-1}{17}+\dfrac{1-5}{25}=-1-\dfrac{7}{17}-\dfrac{4}{25}=-\dfrac{668}{425}\)