a: 2/3=12/x

=>12/x=2/3

hay x=18

b: =>x/12=2/3

hay x=8

c: =>1/x=1/4

hay x=4

d: =>x/125=2/5

nên x=50

a, \(\dfrac{12}{18}=\dfrac{12}{x}\Rightarrow x=18\)

b, \(\dfrac{24}{36}=\dfrac{3x}{36}\Rightarrow3x=24\Leftrightarrow x=8\)

c, \(\dfrac{14}{56}=\dfrac{14}{14x}\Rightarrow14x=56\Leftrightarrow x=4\)

d, \(\dfrac{x}{125}=\dfrac{50}{125}\Rightarrow x=50\)

 x = 18

 x = 8

 x = 4

 x = 50

12 x 56 x 2 + 6 x 14 x 4 + 3 x 30 x 8

= ( 12 x 2 ) x 56 + ( 6 x 4 ) x 14 + ( 3 x 8 ) x 30

= 24 x 56 + 24 x 14 + 24 x 30

= 24 x ( 56 + 14 + 30 )

= 24 x 100

= 2400

và.....

12 x 56 x 2 + 6 x 14 x 4 + 3 x 30 x 8

= 24 x 56 + 24 x 14 + 24 x 30

= 24 x 100

= 2400.( cách này gọn hơn chút )

..........

= ( 12 . 2 ) . 56 + ( 6 . 4 ) . 14 + ( 3 . 8 ) . 30

= 24 . 56 + 24 . 14 + 24 . 30

= 24 . ( 56 + 14 + 30 )

= 24 . 100

= 2400

Bài 1: 

a: -8/12<0<-3/-4

b: -56/24<0<7/3

c: 4/25<1<15/13

=>-4/25>-15/13

Bài 2: 

a: =-60/45=-4/3

b: =4/15-3/2-8/5=8/30-45/30-48/30=-85/30=-17/6

a)ta có: \(\frac{2}{3}=\frac{12}{x}\)

=>2x=3x12

=>x=(3x12):2=18

=>x=18

b)ta có\(\frac{14}{56}=\frac{1}{x}\)

=>14x=56x1

=>x=(56x1):14

=> x=4

k mik nha ^^

a, 2/3=12/18

b,14/56=1/4

a)x=18

b)x=4

 x + 12 = 12

x = 12 - 12

x = 0

x - 12 = 12

x = 12 + 12

x = 24

x + 14 = 56

x = 56 - 14

x = 42

Trao đổi tk

x + 12 = 12            

x        = 12 - 12

x        = 0

x - 12 = 12

x       = 12 + 12

x       = 24

x + 14 = 56

x         = 56 - 14

x        = 42

 k cho mik nhe !

x=12-12

x=0

x=12+12

x=24

x=56-14

x=42

x=

\(\frac{2}{3}=\frac{2.6}{3.6}=\frac{12}{18}\)

\(\frac{14}{56}=\frac{14:14}{56:14}=\frac{1}{4}\)

\(\frac{24}{36}=\frac{24:3}{36:3}=\frac{8}{12}\)

\(\frac{x}{152}=\frac{2}{5}\Rightarrow x.5=2.152\Rightarrow x.5=304\Rightarrow x=304:5=60,8\)

a)\(\frac{2}{3}=\frac{12}{x}\Rightarrow12\times3=2x\)

=>36=2x

=>x=18

b)\(\frac{14}{56}=\frac{1}{4}=\frac{1}{x}\Rightarrow4=x\)

=>x=4

c)\(\frac{24}{36}=\frac{2}{3}=\frac{x}{12}\Rightarrow12\times2=3x\)

=>24=3x

=>x=8

d)\(\frac{x}{152}=\frac{2}{5}\Rightarrow2\times152=5x\)

=>304=5x

=>x=\(\frac{304}{5}\)

a} 12/18=12/x

=> x=18

b}14/56=14/14x

=> 14x=56

=> x=56:14=4

c}24/36=3x/36

=> 3x=24

=> x=24:3

=> x=8

d} ko tồn tại vì 152 ko chia hết cho 5    

\(a)\frac{2}{3}=\frac{12}{x}\)

\(\Rightarrow2\cdot x=12\cdot3\)

\(\Rightarrow2\cdot x=36\)

\(\Rightarrow x=36:2=18\)

Vậy x = 18

\(b)\frac{24}{36}=\frac{x}{12}\)

Rút gọn : \(\frac{24}{36}=\frac{24:12}{36:12}=\frac{2}{3}\)

\(\Rightarrow\frac{2}{3}=\frac{x}{12}\)

\(\Rightarrow2\cdot12=x\cdot3\)

\(\Rightarrow x=\frac{2\cdot12}{3}=8\)

Vậy x = 8

\(c)\frac{14}{56}=\frac{1}{x}\)

Rút gọn : \(\frac{14}{56}=\frac{14:14}{56:14}=\frac{1}{4}\)

\(\Rightarrow\frac{1}{4}=\frac{1}{x}\)

\(\Rightarrow x=4\)

Vậy x = 4

\(d)\frac{x}{125}=\frac{2}{5}\)

\(\Rightarrow x\cdot5=2\cdot125\)

\(\Rightarrow x\cdot5=250\)

\(\Rightarrow x=250:5=50\)

Vậy x = 50

a) x = 18

b) x = 8

c) x = 4

d) x = 50

bạn làm dấu chấm là dấu nhân có phải không 

a.1872

b.3676

2 tui cũng là army yiu bts nhìu 

----jung hosoek---

a) 12 x 13 + 12 x 49 + 12 x 14 +14 x 78 = 1873

b) 34 x 34 + 56 x 45 = 3676

\(1.\text{ Tính : }\)

\(a,\text{ }12\text{ x }13+12\text{ x }49+12\text{ x }14+14\text{ x }78\)

\(=12\text{ x }\left(13+49\right)+14\text{ x }\left(12+78\right)\)

\(=12\text{ x }62+14\text{ x }90\)

\(=744+1260\)

\(=2004\)

\(b,\text{ }34\text{ x }34+56\text{ x }45\)

\(=1156+2520\)

\(=3676\)     

a: =>10|x-2|=50

=>|x-2|=5

=>x-2=5 hoặc x-2=-5

=>x=7 hoặc x=-3

b: =>|3x-12|+|5x-20|=56

=>8|x-4|=56

=>|x-4|=7

=>x-4=7 hoặc x-4=-7

=>x=11 hoặc x=-3