\(=\left(-\dfrac{1}{6}-\dfrac{5}{6}\right)+\left(\dfrac{25}{9}+\dfrac{2}{9}\right)=-1+3=2\)

Câu 6: Tính bằng cách hợp lí:

 25/9 - 1/6 + 4/18 -5/6 = (25/9+4/18)+(-1/6-5/6)

                                   =3-1

                                  =2

\(=\dfrac{25}{9}-\dfrac{1}{6}-\dfrac{2}{9}-\dfrac{5}{6}\\ =\left(\dfrac{25}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{6}-\dfrac{1}{6}\right)\\ =\dfrac{23}{9}+\dfrac{2}{3}\\ =\dfrac{23+6}{9}=\dfrac{29}{9}\)

a: =8/20-5/20+6/20=9/20

b: =-2/5:9/10=-2/5*10/9=-20/45=-4/9

c: =7/8*4/9+1/14*14/5

=28/72+1/5

=53/90

d: =2/7(3/11+8/11)

=2/7

= 3 0 

a) 5

b) 11/6

\(\frac{6}{25}-\frac{81}{25}+\left|-4\right|\cdot\frac{2}{7}-(-2)^3\)

\(\Rightarrow\frac{6-81}{25}+4\cdot\frac{2}{7}-(-2)^3\)

\(=\frac{-75}{25}+\frac{8}{7}+8\)

\(=3+\frac{8}{7}+8=3+8+\frac{8}{7}=11+\frac{8}{7}=\frac{77+8}{7}=\frac{85}{7}\)

\(\frac{6}{25}-\frac{81}{25}+|-4|.\frac{2}{7}-\left(-2\right)^3\)

\(=\frac{6-81}{25}+4.\frac{2}{7}-\left(-8\right)\)

\(=\frac{-75}{25}+\frac{8}{7}+8\)

\(=-3+\frac{8}{7}+8\)

\(=5+\frac{8}{7}=\frac{35}{7}+\frac{8}{7}=\frac{35+8}{7}=\frac{43}{7}\)

Nhầm phần cuối :D ^.^

= \(-3+\frac{8}{7}+8=-3+8+\frac{8}{7}=5+\frac{8}{7}=\frac{43}{7}\)

a: =17/25(13/19+6/19)=17/25

b: \(=\dfrac{47}{19}\cdot\dfrac{32}{15}-\dfrac{47}{19}\cdot\dfrac{17}{15}=\dfrac{47}{19}\)

`17/25xx(13/19+6/19)`

`17/25xx1`

`17/25`

`a)17/25xx13/19+17/25xx6/19`

`=17/25xx(13/19+6/19)`

`=17/25xx19/19=17/25`

`b)47/19:15/32-47/19:15/17`

`=47/19xx32/15-47/19xx17/15`

`=47/19xx(32/15-17/15)`

`=47/19xx15/15=47/19`