a: =-3/24-40/24

=-43/24

b: \(=\dfrac{6}{54}\cdot\dfrac{49}{35}=\dfrac{1}{9}\cdot\dfrac{7}{5}=\dfrac{7}{45}\)

c: \(=\dfrac{6}{5}+\dfrac{4}{3}=\dfrac{18+20}{15}=\dfrac{38}{15}\)

d: \(=\dfrac{31}{17}-\dfrac{14}{17}-\dfrac{5}{13}-\dfrac{8}{13}=1-1=0\)

`31/17+(-5/13)+(-8/3)-14/17`

`=(31/17-14/17)-(5/13-8/3)`

`=17/17-(15/39-104/39)`

`=1-(-89/39)`

`=1+89/39`

`=39/39+89/39`

`=128/39`

a: =35/17-18/17-9/5+4/5

=1-1=0

b: =-7/19(3/17+8/11-1)

=7/19*18/187=126/3553

c: =26/15-11/15-17/3-6/13

=1-6/13-17/3

=7/13-17/3=-200/39

bấm máy tính

tự vận đông đê

a) 12/38

b) 44/18

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

=\(\left[\dfrac{2}{3}+\left(\dfrac{-2}{3}\right)\right]+\dfrac{5}{7}\)

=\(0+\dfrac{5}{7}=\dfrac{5}{7}\)

\(\dfrac{31}{17}+\left(\dfrac{-5}{13}\right)+\left(\dfrac{-8}{13}\right)-\dfrac{14}{17}\)

=\(\left(\dfrac{31}{17}-\dfrac{14}{17}\right)+\left[\left(\dfrac{-5}{13}\right)+\left(\dfrac{-8}{13}\right)\right]\)

=\(1+\left(-1\right)\)

=\(0\)

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

\(\dfrac{31}{17}+\left(-\dfrac{5}{13}\right)+\left(-\dfrac{8}{13}\right)-\dfrac{14}{17}=1-1=0\)

có ai làm đc kkkông

bạn lên mạng tra từng câu 1 sẽ có

ukm cảm ơn bạn nhìu

31/17+(-5/13)+(-8/13)-14/17

=(31/17-14/17)+[-5/13+(-8/13)]

=1+(-1)

=0

\(\frac{31}{17}+\frac{-5}{13}+\frac{-8}{13}-\frac{14}{17}\)

\(=\left[\frac{31}{17}-\frac{14}{17}\right]+\left[\frac{-5}{13}+\frac{-8}{13}\right]\)

\(=1+(-1)=0\)

\(\frac{31}{17}+\frac{-5}{13}+\frac{-8}{13}-\frac{14}{17}\)

\(=\left(\frac{31}{17}-\frac{14}{17}\right)+\left(\frac{-5}{13}+\frac{-8}{13}\right)\)

\(=1+\left(-1\right)\)

\(=0\)

~ Hok tốt ~