Question

Tính nhanh : ( câu C)

Answer 1

`c)D=6/7 . 8/13+6/13 . 9/7-3/13 . 6/7`

   `D=6/13 . 8/7+6/13 . 9/7-6/13 . 3/7`

   `D=6/13 . (8/7+9/7-3/7)`

   `D=6/13 . 14/7`

   `D=6/13 . 2=12/13`

Answer 2

\(D=\dfrac{6}{7}\left(\dfrac{8}{13}-\dfrac{3}{13}\right)+\dfrac{6}{13}.\dfrac{9}{7}=\dfrac{6}{7}.\dfrac{5}{13}+\dfrac{6}{13}.\dfrac{9}{7}=\dfrac{30}{91}+\dfrac{54}{91}=\dfrac{84}{91}=\dfrac{12}{13}\)

Answer 3

\(D=\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{3}{13}.\dfrac{6}{7}\)

\(\Rightarrow D=\dfrac{6}{13}.\dfrac{8}{7}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{3}{7}.\dfrac{6}{13}\)

\(\Rightarrow D=\dfrac{6}{13}\left(\dfrac{8}{7}+\dfrac{9}{7}-\dfrac{3}{7}\right)\)

\(\Rightarrow D=\dfrac{6}{13}.2=\dfrac{12}{13}\)