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27 tháng 8 2020

Bài làm:

Ta có: \(3\cdot\left(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}\right)=\frac{60}{15}\)

\(\Leftrightarrow3x\cdot\left(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}\right)=4\)

\(\Leftrightarrow x\cdot\left(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}\right)=4\)

\(\Leftrightarrow x\cdot\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}\right)=4\)

\(\Leftrightarrow x\cdot\left(1-\frac{1}{13}\right)=4\)

\(\Leftrightarrow x\cdot\frac{12}{13}=4\)

\(\Rightarrow x=\frac{13}{3}\)

27 tháng 8 2020

Ta có : \(3\times\left(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}\right)=\frac{60}{15}\)

=> \(3\times x\times\left(\frac{1}{4}+\frac{1}{28}+\frac{1}{70}+\frac{1}{130}\right)=4\)

=> \(x\times\left(\frac{3}{4}+\frac{3}{28}+\frac{3}{70}+\frac{3}{130}\right)=4\)

=> \(x\times\left(\frac{3}{1\times4}+\frac{3}{4\times7}+\frac{3}{7\times10}+\frac{3}{10\times13}\right)=4\)

=> \(x\times\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}\right)=4\)

=> \(x\times\left(1-\frac{1}{13}\right)=4\)

=> \(x\times\frac{12}{13}=4\)

=> \(x=4:\frac{12}{13}\)

=> \(x=\frac{13}{3}\)

24 tháng 9 2023

a) \(\dfrac{6}{13}:\left(\dfrac{1}{2}-x\right)=\dfrac{15}{39}\)

\(\dfrac{1}{2}-x=\dfrac{6}{13}:\dfrac{15}{39}\)

\(\dfrac{1}{2}-x=\dfrac{6}{5}\)

\(x=\dfrac{1}{2}-\dfrac{6}{5}\)

\(x=-\dfrac{7}{10}\)

b) \(3\times\left(\dfrac{x}{4}+\dfrac{x}{28}+\dfrac{x}{70}+\dfrac{x}{130}\right)=\dfrac{60}{13}\)

\(3\times x\times\left(\dfrac{1}{4}+\dfrac{1}{28}+\dfrac{1}{70}+\dfrac{1}{130}\right)=\dfrac{60}{13}\)

\(x\times\left(\dfrac{3}{1\times4}+\dfrac{3}{4\times7}+\dfrac{3}{7\times10}+\dfrac{3}{7\times13}\right)=\dfrac{60}{13}\)

\(x\times\left(1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{13}\right)=\dfrac{60}{13}\)

\(x\times\left(1-\dfrac{1}{13}\right)=\dfrac{60}{13}\)

\(x\times\dfrac{12}{13}=\dfrac{60}{13}\)

\(x=\dfrac{60}{13}:\dfrac{12}{13}\)

\(x=5\)

30 tháng 5 2021

`3 xx (x/4 + x/28 + x/70 + x/130) =60/13`

`x/4 + x/28 + x/70 + x/130 = 20/13`

`x xx (1/4+1/28+1/70+1/130)=20/13`

`x xx 4/13= 20/13`

`x=5`

22 tháng 2 2022

`3 xx (x/4 + x/28 + +x/70 +x/130) =60/13`

`x xx (1/4 + 1/28 + +1/70 +1/130)=20/13

`x xx 4/13 = 20/13`

`x=5`

30 tháng 7 2020

\(3\times\left(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}\right)=\frac{60}{13}\)

=> \(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}=\frac{20}{13}\)

=> \(\frac{x}{1\cdot4}+\frac{x}{4\cdot7}+\frac{x}{7\cdot10}+\frac{x}{10\cdot13}=\frac{20}{13}\)

=> \(\frac{x}{3}\left(\frac{3}{1\cdot4}+\frac{3}{4\cdot7}+\frac{3}{7\cdot10}+\frac{3}{10\cdot13}\right)=\frac{20}{13}\)

=> \(\frac{x}{3}\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{10}-\frac{1}{13}\right)=\frac{20}{13}\)

=> \(\frac{x}{3}\left(1-\frac{1}{13}\right)=\frac{20}{13}\)

=> \(\frac{x}{3}\cdot\frac{12}{13}=\frac{20}{13}\)

=> \(\frac{x}{3}=\frac{20}{13}:\frac{12}{13}=\frac{20}{13}\cdot\frac{13}{12}=\frac{5}{3}\)

=> x = 5

\(3\cdot\left(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}\right)=\frac{60}{13}\)

\(3\cdot\left(\frac{x}{1\cdot4}+\frac{x}{4\cdot7}+\frac{x}{7\cdot10}+\frac{x}{10\cdot13}\right)=\frac{60}{13}\)

\(3\left(x-3\right)\left(\frac{3}{1\cdot4}+\frac{3}{4\cdot7}+\frac{3}{7\cdot10}+\frac{3}{10\cdot13}\right)=\frac{60}{13}\)

\(\left(3x-9\right)\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}\right)=\frac{60}{13}\)

\(\left(3x-9\right)\left(1-\frac{1}{13}\right)=\frac{60}{13}\)

\(\left(3x-9\right)\cdot\frac{12}{13}=\frac{60}{13}\)

\(3x-9=\frac{\frac{60}{13}}{\frac{12}{13}}\)

\(3x-9=5\)

\(3x=5+9\)

\(3x=14\)

\(x=\frac{14}{3}\approx4,667\)

11 tháng 6 2021

\(52:x=\frac{1}{4}+\frac{1}{28}+\frac{1}{70}+\frac{1}{130}\)

\(52:x=\frac{1}{1\times4}+\frac{1}{4\times7}+\frac{1}{7\times10}+\frac{1}{10\times13}\)

\(52:x=\frac{1}{3}\times\left(\frac{3}{1\times4}+\frac{3}{4\times7}+\frac{3}{7\times10}+\frac{3}{10\times13}\right)\)

\(52:x=\frac{1}{3}\times\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}\right)\)

\(52:x=\frac{1}{3}\times\left(1-\frac{1}{13}\right)\)

\(52:x=\frac{1}{3}\times\frac{12}{13}\)

\(52:x=\frac{4}{13}\)

\(x=52:\frac{4}{13}\)

\(x=169\)

52 :x =1/4 + 1/28 +1/70 + 1/130

52 : x = 4/13

x = 52 : 4/13

x = 169

13 tháng 8 2017

tinh trong ngoac truoc =12/3 nhan cho x

suy ra lay 36 : 12/3=9

13 tháng 8 2017

con bai b ban ket hop cac gia tri la voi nhau vi phep cong co tinh chat ket hop

lay x*57+x*50-x*7=x*57+50-7=x*100

x nhan 100 = 10000
suy ra x bang 100

thu lai ket qua di minh chac la dung

AH
Akai Haruma
Giáo viên
28 tháng 1

Lời giải:

\((50\times 60\times 70\times 80):(15\times 25\times 28\times 20)\\ =(50:25)\times (60:15)\times (70:28)\times (80:20)\\ =2\times 4\times \frac{5}{2}\times 4=80\)

11 tháng 9 2015

2x - 35 = 15

      2x = 15 + 35 

      2x = 50

        x = 50 : 2

        x = 25 

11 tháng 9 2015

( x - 1 ) + 5 = 17

          x - 1 = 17 - 5 

          x - 1 = 12

               x = 12 + 1

               x = 13 

11 tháng 7 2019

a) (x.7 +8):5=10

x.7 +8= 10.5=50

x.7= 50-8=42

x= 42:7=6

b) 280: (7+3.x)=4

7+3.x= 4.280= 1120

3.x= 1120-7 =1113

x= 1113: 3= 371

c)  (x.5) .19:13= 57

(x.5). 19= 57.13= 741

x.5= 741: 19= 39

x= 39:5 =7,8

d)  6.(28-8).x = 72

20.x= 72:6= 12

x= 12: 20= 0,6

e) 4. (36-4.x)= 3,2

36-4.x= 32:4= 0,8

-4.x= 0,8- 36= -35,2

x= -35,2 : -4 = 8,8

f) (x-15).3 :12= 6

(x-15).3 = 6. 12= 72

x-15= 72: 3= 24

x= 24+ 15= 39

g)  (x:4+ 6) . 7 = 70

x:4+6= 70:7= 10

x:4= 10-6= 4

x= 4.4 = 16

h)  (x:2+50) :5= 12

x:2+ 50= 12.5= 60

x:2= 60-50= 10

x= 10.2=20

l) 5.(7+3.x)= 140

7+3.x= 140:5 = 28

3.x= 28-7 =21

x= 21: 3= 7

k cho mình nhe

8 tháng 9 2019

7/4 tru 4/3 nhan y bang 5/19