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a: x-4/5=3/7

=>x=3/7+4/5=43/35

b: x+3/7=4/5

=>x=4/5-3/7=13/35

c: 19/20-x=8/5-3/4

=>19/20-x=32/20-15/20=17/20

=>x=2/20=1/10

d: =>4/5*x=2/21

=>x=2/21:4/5=5/42

e: =>x:7/9=6/8

=>x=6/8*7/9=3/4*7/9=21/36=7/12

f: =>x/6=2/3-1/3=1/3

=>x=2

a: x-4/5=3/7

=>x=3/7+4/5=43/35

b: x+3/7=4/5

=>x=4/5-3/7=13/35

c: 19/20-x=8/5-3/4

=>19/20-x=32/20-15/20=17/20

=>x=2/20=1/10

d: =>4/5*x=11/21

=>x=55/84

e: =>x=6/8*7/9=42/72=7/12

f: =>x/6=2/3-1/3=1/3

=>x=2

17 tháng 4 2022

x - 4/5 = 3/7

x = 3/7 + 4/5

x = 43/35

x + 3/7 = 4/5

x = 4/5 - 3/7

x = 13/35

19/20 - x = 8/5 - 3/4

19/20 - x =  17/20

x = 19/20 - 17/20

x = 2/20 = 1/10

4/5 x X = 6/9 - 4/7

4/5 x X = 2/21

x = 2/21 : 4/5

x =5/42

x : 7/9 = 6/8

x = 6/8 x 7/9

x = 7/12

2/3 - x/6 = 6/18

x/6 = 2/3 - 6/18

x/6 = 1/3

x/6 = 2/6

=> x =2

17 tháng 4 2022

1. x = 43/35

2. x = 13/35

3. x = 1/10

còn lại tự tính nhá

tui bận òi

HQ
Hà Quang Minh
Giáo viên
2 tháng 8 2023

\(3\cdot\left(\dfrac{1}{2}-x\right)-5\left(x-\dfrac{1}{10}\right)=-\dfrac{7}{4}\\ \Leftrightarrow-8x=-\dfrac{15}{4}\\ \Leftrightarrow x=\dfrac{15}{32}\)

 

\(4\left(\dfrac{3}{4}+x\right)-\dfrac{1}{5}=7x-\dfrac{1}{7}\\ \Leftrightarrow3x=\dfrac{103}{35}\\ \Leftrightarrow x=\dfrac{103}{105}\)

2 tháng 8 2023

\(3\left(\dfrac{1}{2}-x\right)-5\left(x-\dfrac{1}{10}\right)=-\dfrac{7}{4}\)

\(\Rightarrow\dfrac{3}{2}-3x-5x+\dfrac{1}{2}=-\dfrac{7}{4}\)

\(\Rightarrow2-8x=-\dfrac{7}{4}\)

\(\Rightarrow8x=2+\dfrac{7}{4}\)

\(\Rightarrow8x=\dfrac{15}{4}\)

\(\Rightarrow x=\dfrac{15}{32}\)

___________

\(4\left(\dfrac{3}{4}+x\right)-\dfrac{1}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow3+4x-\dfrac{1}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow4x+\dfrac{14}{5}=7x-\dfrac{1}{7}\)

\(\Rightarrow7x-4x=\dfrac{14}{5}+\dfrac{1}{7}\)

\(\Rightarrow3x=\dfrac{103}{35}\)

\(\Rightarrow x=\dfrac{103}{105}\)

9 tháng 12 2015

 

1.x=4

2.x=6

3.x=8

24 tháng 10 2021

1: \(\dfrac{4}{23}+\dfrac{5}{21}+\dfrac{1}{2}-\dfrac{4}{23}+\dfrac{16}{21}\)

\(=1+\dfrac{1}{2}\)

\(=\dfrac{3}{2}\)

2: \(\left(\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}\right)-\left(\dfrac{79}{67}-\dfrac{28}{41}\right)\)

\(=\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}-\dfrac{79}{67}+\dfrac{28}{41}\)

\(=\dfrac{1}{3}\)

10 tháng 8 2016

a)(x+28):13=25,2

x+28=25,2.13

x+28=327,6

x=327,6-28

x=299,6

b)(7x+6)*5^5=5^8

7x+6=5^8:5^5

7x+6=5^3

7x+6=125

7x=125-6

7x=119

x=119:7

x=17

c)(x-3)^2-23=2

(x-3)^2=2+23

(x-3)^2=25

x-3=5

x=5+3

x=8

d)3^30(x-2)=(3^32-3^31)

3^30(x-2)=3^1

x-2=3^1:3^30

x-2=3-29

x=3-29+2

a: \(\Leftrightarrow3x^3-2x^2+15x^2-10x+3x-2+7⋮3x-2\)

\(\Leftrightarrow3x-2\in\left\{1;-1;7;-7\right\}\)

hay \(x\in\left\{3;1\right\}\)

b: \(\Leftrightarrow2x^5-7x^3+4x^4-14x^2+14x^2-49x+49x-44⋮2x^2-7\)

\(\Leftrightarrow2401x^2-1936⋮2x^2-7\)

\(\Leftrightarrow4802x^2-3872⋮2x^2-7\)

\(\Leftrightarrow2x^2-7\inƯ\left(12935\right)\)

\(\Leftrightarrow2x^2-7\in\left\{1;5;13;65;199;995;2587;12935;-1;-5\right\}\)

\(\Leftrightarrow2x^2\in\left\{8;72;2\right\}\)

hay \(x\in\left\{2;-2;6;-6;1;-1\right\}\)

17 tháng 2 2020

\(\frac{x-23}{24}+\frac{x-23}{25}=\frac{x-23}{26}\)

\(\Leftrightarrow\frac{x-23}{24}+\frac{x-23}{25}-\frac{x-23}{26}=0\)

\(\Leftrightarrow\left(x-23\right)\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}\right)=0\)

\(\Leftrightarrow x-23=0\left(vì\frac{1}{24}+\frac{1}{25}-\frac{1}{26}\ne0\right)\)

\(\Leftrightarrow x=23\)

vậy................

\(\frac{201-x}{99}+\frac{203-x}{97}+\frac{205-x}{95}+3=0\)

\(\Leftrightarrow\left(\frac{201-x}{99}+1\right)+\left(\frac{203-x}{97}+1\right)+\left(\frac{205-x}{95}+1\right)=0\)

\(\Leftrightarrow\frac{300-x}{99}+\frac{300-x}{97}+\frac{300-x}{95}=0\)

\(\Leftrightarrow\left(300-x\right)\left(\frac{1}{99}+\frac{1}{97}+\frac{1}{95}\right)=0\)

\(\Leftrightarrow300-x=0\left(vì\frac{1}{99}+\frac{1}{97}+\frac{1}{95}>0\right)\)

\(\Leftrightarrow x=300\)

vậy..........