Question

[Nguyễn Thị Gia Linh]

 

Mn ơi,giúp mk mấy câu này đc ko?

Answer 1

[『Kuroba ム Tsuki Ryoo ︵²ᵏ⁷』]

`#3107.101107`

`g)`

\(\dfrac{4}{19}\cdot\dfrac{-3}{7}+\dfrac{-3}{7}\cdot\dfrac{15}{19}+\dfrac{5}{7}\)

\(=\dfrac{-3}{7}\left(\dfrac{4}{19}+\dfrac{15}{19}\right)+\dfrac{5}{7}\)

\(=\dfrac{-3}{7}\cdot1+\dfrac{5}{7}\)

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

`h)`

\(\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{9}{13}-\dfrac{5}{9}\cdot\dfrac{3}{13}\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{9}{13}-\dfrac{3}{13}\right)\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{7+9-3}{13}\right)\)

\(=\dfrac{5}{9}\cdot1=\dfrac{5}{9}\)

`i)`

\(\left(\dfrac{-4}{5}+\dfrac{4}{3}\right)+\left(\dfrac{-5}{4}+\dfrac{14}{5}\right)-\dfrac{7}{3}\)

\(=\dfrac{-4}{5}+\dfrac{4}{3}+\dfrac{-5}{4}+\dfrac{14}{5}-\dfrac{7}{3}\)

\(=\left(-\dfrac{4}{5}+\dfrac{14}{5}\right)+\left(\dfrac{4}{3}-\dfrac{7}{3}\right)-\dfrac{5}{4}\)

\(=\dfrac{10}{5}+\dfrac{-3}{3}-\dfrac{5}{4}\)

\(=2-1-\dfrac{5}{4}\)

\(=1-\dfrac{5}{4}\)

\(=-\dfrac{1}{4}\)

`j)`

\(\dfrac{8}{3}\cdot\dfrac{2}{5}\cdot\dfrac{3}{8}\cdot10\cdot\dfrac{19}{92}\)

\(=\left(\dfrac{8}{3}\cdot\dfrac{3}{8}\right)\cdot\left(\dfrac{2}{5}\cdot10\right)\cdot\dfrac{19}{92}\)

\(=1\cdot\dfrac{20}{5}\cdot\dfrac{19}{92}\)

\(=4\cdot\dfrac{19}{92}=\dfrac{19}{23}\)

`k)`

\(\dfrac{-5}{7}\cdot\dfrac{2}{11}+\dfrac{-5}{7}\cdot\dfrac{9}{14}+1\dfrac{5}{7}\)

\(=-\dfrac{5}{7}\cdot\dfrac{2}{11}-\dfrac{5}{7}\cdot\dfrac{9}{14}+1+\dfrac{5}{7}\)

\(=\dfrac{5}{7}\cdot\left(-\dfrac{2}{11}-\dfrac{9}{14}+1\right)+1\)

\(=\dfrac{5}{7}\cdot\dfrac{27}{154}+1\)

\(=\dfrac{135}{1078}+1=\dfrac{1213}{1078}\)

`l)`

\(\dfrac{12}{19}\cdot\dfrac{7}{15}\cdot\dfrac{-13}{17}\cdot\dfrac{19}{12}\cdot\dfrac{17}{13}\)

\(=\left(\dfrac{12}{19}\cdot\dfrac{19}{12}\right)\cdot\left(-\dfrac{13}{17}\cdot\dfrac{17}{13}\right)\cdot\dfrac{7}{15}\)

\(=1\cdot\left(-1\right)\cdot\dfrac{7}{15}=-\dfrac{7}{15}\)

Answer 2

[Nguyễn Thị Gia Linh]

sos