các bạn giúp mình nhnh với ạ , cảm ơn các bạn nhiều
`(-3)/7+15/26+(-2/13+3/7)`
`=(-3)/7+3/7+15/(26)-2/13`
`=15/26-4/26=11/26`
`(-4)/5*11/13+4/5*(-2)/13-1/5`
`=(-4)/5*(11/13+2/13)-1/5`
`=(-4)/5-1/5=-1`
Giải:
\(\dfrac{-3}{7}+\dfrac{15}{26}+\left(\dfrac{-2}{13}+\dfrac{3}{7}\right)\)
\(=\dfrac{-3}{7}+\dfrac{15}{26}+\dfrac{-2}{13}+\dfrac{3}{7}\)
\(=\left(\dfrac{-3}{7}+\dfrac{3}{7}\right)+\left(\dfrac{15}{26}+\dfrac{-2}{13}\right)\)
\(=0+\dfrac{11}{26}\)
\(=\dfrac{11}{26}\)
\(\dfrac{-4}{5}.\dfrac{11}{13}+\dfrac{4}{5}.\dfrac{-2}{13}-\dfrac{1}{5}\)
\(=\dfrac{-4}{5}.\dfrac{11}{13}+\dfrac{-4}{5}.\dfrac{2}{13}-\dfrac{1}{5}\)
\(=\dfrac{-4}{5}.\left(\dfrac{11}{13}+\dfrac{2}{13}\right)-\dfrac{1}{5}\)
\(=\dfrac{-4}{5}.1-\dfrac{1}{5}\)
\(=\dfrac{-4}{5}-\dfrac{1}{5}\)
\(=-1\)
Chúc bạn học tốt!
