LB

\(-\dfrac{6}{13}\) . \(\dfrac{13}{21}\) + \(\dfrac{6}{13}\) . \(-\dfrac{8}{21}\)

 
T3
19 tháng 8 lúc 12:14

\(-\dfrac{6}{13}.\dfrac{13}{21}+\dfrac{6}{13}.-\dfrac{8}{21}\)
\(=\dfrac{6}{13}.\dfrac{-13}{21}+\dfrac{6}{13}.\dfrac{-8}{21}\)
\(=\dfrac{6}{13}.\left(\dfrac{-13}{21}+\dfrac{-8}{21}\right)\)
\(=\dfrac{6}{13}.\dfrac{-21}{21}\)
\(=\dfrac{6}{13}.\left(-1\right)\)
\(=\dfrac{-6}{13}\)

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KS
19 tháng 8 lúc 12:21

`-6/13 . 13/21 + 6/13 . -8/21`

`= -6/13 . 13/21 - 6/13 . 8/21`

`= -6/13 . (13/21 + 8/21)`

`= -6/13 . 21/21`

`= -6/13 . 1`

`= -6/13`

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