a)3/10-(-5/6-7/15) c)-8/13.3/4+-8/13.-5/6- -8/13
=3/10-(-25/30-14/30) =-8/13.(3/4+ -5/6)
=3/10- -39/30 =-8/13.(18/24+ -20/24)
=9/30- -39/30 =-8/13. -2/24
=48/30 =-2/39
Mình chỉ làm đc 2 câu này thôi .Chúc you hk tốt để vượt qua kì thi cuối kì 2 nhá !!!
b)19/13-6/13+(-11) d)2/5+3/5.(-2+9/7)
=-1+(-11) =1.( -14/7+9/7)
=-10 =1.-5/7=-5/7
a) \(\dfrac{3}{10}-\left(\dfrac{-5}{6}-\dfrac{7}{15}\right)\)
\(=\dfrac{3}{10}-\left(\dfrac{-25}{30}-\dfrac{14}{30}\right)\)
\(=\dfrac{3}{10}-\dfrac{-39}{30}\)
\(=\dfrac{9}{30}-\dfrac{-39}{30}\)
\(=\dfrac{48}{30}=\dfrac{8}{5}\)
b) \(\dfrac{19}{13}-\dfrac{6}{13}+\left(-11\right)\)
\(=1+\left(-11\right)\)
\(=-10\)
c) \(\dfrac{-8}{13}.\dfrac{3}{4}+\dfrac{-8}{13}.\dfrac{-5}{6}-\dfrac{-8}{13}\)
\(=\dfrac{-8}{13}.\left(\dfrac{3}{4}+\dfrac{-5}{6}\right)-\dfrac{-8}{13}\)
\(=\dfrac{-8}{13}.\left(\dfrac{18}{24}+\dfrac{-20}{24}\right)-\dfrac{-8}{13}\)
\(=\dfrac{-8}{13}.\dfrac{-1}{12}-\dfrac{-8}{13}\)
\(=\dfrac{8}{156}-\dfrac{-8}{13}\)
\(=\dfrac{2}{39}-\dfrac{-8}{13}\)
\(=\dfrac{2}{39}-\dfrac{-24}{39}\)
\(=\dfrac{26}{39}=\dfrac{2}{3}\)
a) \(\dfrac{3}{10}-\left(\dfrac{-5}{6}-\dfrac{7}{15}\right)\)
\(=\dfrac{3}{10}-\dfrac{-13}{10}\)
\(=\dfrac{8}{5}\)
b) \(\dfrac{19}{13}-\dfrac{6}{13}+\left(-11\right)\)
\(=\left(\dfrac{19}{13}-\dfrac{6}{13}\right)+\left(-11\right)\)
\(=1+\left(-11\right)\)
\(=-10\)
c) \(\dfrac{-8}{13}.\dfrac{3}{4}+\dfrac{-8}{13}.\dfrac{-5}{6}-\dfrac{-8}{13}\)
\(=\dfrac{-8}{13}.\left(\dfrac{3}{4}+\dfrac{-5}{6}-1\right)\)
\(=\dfrac{-8}{13}.\dfrac{-13}{12}\)
\(=\dfrac{2}{3}\)
d) \(\dfrac{2}{5}+\dfrac{3}{5}.\left(-2+\dfrac{9}{7}\right)\)
\(=\dfrac{2}{5}+\dfrac{3}{5}.\dfrac{-5}{7}\)
\(=\dfrac{2}{5}+\dfrac{-3}{7}\)
\(=\dfrac{-1}{35}\)
