Question

[Trần Thị Thảo]

Thực hiện phép tính (tính hợp lý nếu có thể): 

a) \(\dfrac{5}{9}.\dfrac{7}{13}+\dfrac{5}{9}.\dfrac{8}{13}-\dfrac{5}{13}.\dfrac{2}{9}\)             b) \(12\dfrac{5}{14}-\left(3\dfrac{5}{7}+5\dfrac{5}{14}\right)\) 

c)\(\dfrac{-2}{5}+\dfrac{7}{11}+\dfrac{-11}{10}+\dfrac{7}{-11}\)             d) \(\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}+\dfrac{-2}{5}\) 

Answer 1

[Nguyễn Lê Phước Thịnh]

b: =12+5/14-3-5/7-5-5/14

=4-5/7

=28/7-5/7=23/7

c: =(-2/5-11/10)+(7/11-7/11)

=-4/10-11/10=-15/10=-3/2

Answer 2

[Knight™]

\(a,\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{5}{13}\cdot\dfrac{2}{9}\)

\(=\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{2}{13}\cdot\dfrac{5}{9}\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{8}{13}-\dfrac{2}{13}\right)\)

\(=\dfrac{5}{9}\cdot\dfrac{14}{13}\)

\(=\dfrac{70}{117}\)

\(d,\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}+\dfrac{-2}{5}\)

\(=\left(\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}\right)+\dfrac{-2}{5}\)

\(=0+\dfrac{-2}{5}\)

\(=\dfrac{-2}{5}\)