`#lv`

`-2/5+(-7/10)-9/6`

`=-2/5-7/10-9/6`

`=-4/10-7/10-9/6`

`=-11/10-3/2`

`=-11/10-15/10`

`=-26/10`

`=-13/5`

__

`1/2+(-2/5)-(-2/3)`

`=1/2-2/5+2/3`

`=5/10-4/10+2/3`

`=1/10+2/3`

`=3/30+20/30`

`=23/30`

__

`5/3-3/4+7/6`

`=20/12-9/12+14/12`

`=11/12+14/12`

`=25/12`

__

`-1/5+5/3-3/2`

`=-3/15+25/15-3/2`

`=22/15-3/2`

`=44/30-45/30`

`=-1/30`

__

`1/4-7/8+(-9/10)`

`=2/8-7/8-9/10`

`=-5/8-9/10`

`=-25/40-36/40`

`=-61/40`

__

`5/4+1/2+(-7/12)`

`=15/12+6/12-7/12`

`=21/12-7/12`

`=14/12`

`=7/6`

__

`-5/8-1/3+(-7/6)`

`=-5/8-1/3-7/6`

`=-15/24-8/24-28/24`

`=-52/24`

`=-13/6`

__

`-3/4-7/10+(-5/6)`

`=-3/4-7/10-5/6`

`=-45/60-42/60-50/60`

`=-137/60`

Bài làm

a, (-2/5) + (-7/10) - 9/6 =(-12/30) + (-21/30) - 45/30=(-33/30) - 45/30 = (-78/30)

b,1/2 + (-2/5) - (-2/3) = 15/30 + (-12/30) - (-20/30) = 3/30 - (-20/30) = 23/30

c,5/3 - 3/4 + 7/6 = 40/24 - 18/24 + 28/24 = 22/24 + 28/24 = 50/24 = 25/12

d, (-1/5) + 5/3 - 3/2 = (-6/30) + 50/30 - 45/30 = 44/30 - 45/30 = (-1/30)

e, 1/4 - 7/8 + (-9/10) = 10/40 - 35/40 - 36/40 = (-25/40) - 36/40 = (-61/40)

f, 5/4 +1/2 + (-7/12) = 15/12 + 6/12 - 7/12 = 21/12 - 7/12 = 14/12 = 7/6

g,(-5/8) -1/3 + (-7/6) = (-15/24) - 8/24 - 28/24 = (-23/24) - 28/24 = (-51/24) 

k,(-3/4) - 7/10 + (-5/6) = (-45/60) - 42/60 - 50/60 = (-87/60) - 50/60 = (-137/60)

chúc bn học tốt nha

sai thì mn góp ý giúp mk

\(C=5\frac{9}{10}:\frac{3}{2}-\left(2\frac{1}{3}.4\frac{1}{2}-2.2\frac{1}{3}\right):\frac{7}{4}\)

\(=\frac{59}{10}:\frac{3}{2}-\left(\frac{7}{3}.\frac{9}{2}-2.\frac{7}{3}\right):\frac{7}{4}\)

\(=\frac{59}{15}-\left[\frac{7}{3}\left(\frac{9}{2}-2\right)\right]:\frac{7}{4}\)

\(=\frac{59}{15}-\frac{35}{6}:\frac{7}{4}\)

\(=\frac{59}{15}-\frac{10}{3}\)

\(=\frac{9}{15}=\frac{3}{5}\)

\(\cdot62,87+35,14+4,13+8,35+4,86+5,65\)

\(=\left(62,87+4,13\right)+\left(35,14+4,86\right)+\left(8,35+5,65\right)\)

\(=67+40+14\)

\(=121\)

a)  -1/8 -2x/5-1/3=3

-2x/5=3+1/8+1/3

-2x/5=83/24

-2x=(83×5)/24=415/24

x = (415÷-2)/24= -415/48

b) -7/3 -(25/6 -4/3+ 3/2)

= -7/3 -13/3 = -20/3

ai ma co 10 k ban chac ban phai lap chuc nink thui

Làm như zậy bạn nhé ^_^"

Đặt :

\(A=\left(\frac{1}{1}.\frac{1}{2}+\frac{1}{2}.\frac{1}{3}+\frac{1}{3}.\frac{1}{4}+\frac{1}{4}.\frac{1}{5}+\frac{1}{5}.\frac{1}{6}\right)\)

\(A=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{5.6}\)( mik lười viết bạn thông cảm nhé !!! )

\(A=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{5}-\frac{1}{6}\)

\(A=\frac{1}{1}-\frac{1}{6}\)

\(A=\frac{5}{6}\)

Thay A vào biểu thức :

Ta có : \(\frac{5}{6}.10-x=0\)

=> \(\frac{25}{3}=x+0\)

=> \(x=\frac{25}{3}\)

(1/1*1/2+1/2*1/3+1/3*1/4+1/4*1/5+1/5*1/6)*10-x=0

=> (1/1.2+1/2.3+1/3.4+1/4.5+1/5.6)*10-x=0

=> (1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6)*10-x=0

=> (1-1/6)*10-x=0

=> 5/6*10-x=0

=> 25/3-x =0

=> x=0+25/3

=> x=25/3

Vậy x=25/3

\(4+2+3=\left(4-2\right)+3=5\)

\(8+4+6=\left(8-4\right)+6=10\)

\(3+2+1=\left(3-2\right)+1=2\)

\(\Rightarrow6+4+2=\left(6-4\right)+2=4\)

k nhé

\(\Rightarrow6+4+2=4\)

6 + 4 + 2 = 4

a) 3/5:3/4=3/5x4/3=(3x4)/(5x3)=12/15=4/5

b)2/5:3/10=2/5x10/3=(2x10)/(5x3)=20/15=4/3

c)9/8:3/4=9/8x4/3=(9x4)/(8x3)=36/32=9/8

d)1/4:1/2=1/4x2=2/4=1/2

e)1/8:1/6=1/8x6=6/8=3/4

g)1/5:1/10=1/5x10=10/5=2

a) 3/5 : 3/4 = 4/5

b) 2/5 : 3/10 = 4/3

c) 9/8 : 3/4 = 3/2

d)  1/4 : 1/2 = 1/2

e) 1/8 : 1/6 = 3/4

g) 1/5 : 1/10 = 2

tk tớ nha

a)3/5:3/4=3/5x4/3=12/15=4/5

b)2/5:3/10=2/5x10/3=20/15=5/3

c)9/8:3/4=9/8x4/3=36/24=3/2

d)1/4:1/2=1/4x2=1/2

e)1/8:1/6=1/8x6=3/4

g)1/5:1/10=1/5x10=2

a) 4+2/5=22/5

b) 5/4+2=13/4

c) 3+3/2=9/2

d) 3/4-1/8=5/8

e) 17/15-7/10=13/30

g) 25/12-15/8=5/24

h) 5-4/3=11/3

i)15/4-3=3/4

a)\(\dfrac{4}{1}+\dfrac{2}{5}=\dfrac{20}{5}+\dfrac{2}{5}=\dfrac{22}{5}\)

b)\(\dfrac{5}{4}+\dfrac{2}{1}=\dfrac{5}{4}+\dfrac{8}{4}=\dfrac{13}{4}\)

c)\(\dfrac{3}{1}+\dfrac{3}{2}=\dfrac{6}{2}+\dfrac{3}{2}=\dfrac{9}{2}\)

d)\(\dfrac{3}{4}-\dfrac{1}{8}=\dfrac{6}{8}-\dfrac{1}{8}=\dfrac{5}{8}\)

e)\(\dfrac{17}{15}-\dfrac{7}{10}=\dfrac{34}{30}-\dfrac{21}{30}=\dfrac{13}{30}\)

g)\(\dfrac{25}{12}-\dfrac{15}{8}=\dfrac{50}{24}-\dfrac{45}{24}=\dfrac{5}{24}\)

h)\(\dfrac{5}{1}-\dfrac{4}{3}=\dfrac{15}{3}-\dfrac{4}{3}=\dfrac{11}{3}\)

i)\(\dfrac{15}{4}-\dfrac{3}{1}=\dfrac{15}{4}-\dfrac{12}{4}=\dfrac{3}{4}\)

4/1+2/5= 20/5+2/5= 22/5

5/4+2/1= 5/4+ 8/4= 13/4

3/1+3/2= 6/2+ 3/2= 9/2

6/8- 1/8= 5/8

34/30- 21/30= 13/30

50/24- 45/24= 5/24

5/1- 4/3= 15/3- 4/3= 11/3

15/4- 3/1= 15/4- 12/4= 3/4