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21 tháng 6 2018

a. x - 1/4 = 5/3

      x = 5/3 + 1/4

      x = 23/12

b. x : 2/3 = 1/3

      x = 1/2 x 2/3

      x = 1/3

4 tháng 11 2023

Bài 1

a) 3 2/5 - 1/2

= 17/5 - 1/2

= 34/10 - 5/10

= 29/10

b) 4/5 + 1/5 × 3/4

= 4/5 + 3/20

= 16/20 + 3/20

= 19/20

c) 3 1/2 × 1 1/7

= 7/2 × 8/7

= 4

d) 4 1/6 : 2 1/3

= 25/6 : 7/3

= 25/14

4 tháng 11 2023

Bài 2

a) 3 × 1/2 + 1/4 × 1/3

= 3/2 + 1/12

= 18/12 + 1/12

= 19/12

b) 1 4/5 - 2/3 : 2 1/3

= 9/5 - 2/3 : 7/3

= 9/5 - 2/7

= 63/35 - 10/35

= 53/35

 

6 tháng 3 2022

Bạn chia từng bài ra được chứ?

22 tháng 8 2023

\(a,x+\dfrac{1}{4}\times\dfrac{1}{5}=\dfrac{4}{5}\)

\(x+\dfrac{1}{20}=\dfrac{4}{5}\)

\(x=\dfrac{4}{5}-\dfrac{1}{20}\)

\(x=\dfrac{16}{20}-\dfrac{1}{20}\)

\(x=\dfrac{15}{20}=\dfrac{3}{4}\)

\(b,3\dfrac{2}{3}:x=2\dfrac{2}{3}-1\dfrac{1}{2}\)

\(\dfrac{11}{3}:x=\dfrac{8}{3}-\dfrac{3}{2}\)

\(\dfrac{11}{3}:x=\dfrac{7}{6}\)

\(x=\dfrac{11}{3}:\dfrac{7}{6}=\dfrac{22}{7}\)

a: =>x+1/20=4/5

=>x=4/5-1/20=16/20-1/20=15/20=3/4

b: =>11/3:x=8/3-3/2=16/6-9/6=7/6

=>x=11/3:7/6=11/3*6/7=66/21=22/7

17 tháng 8 2023

a)

`x+1/4xx1/5=4/5`

`x+1/20=4/5`

`x=4/5-1/20`

`x=16/20-1/20`

`x=15/20=3/4`

b)

`3 2/3:x=2 2/3-1 1/2`

`11/3:x=8/3-3/2`

`11/3:x=16/6-9/6`

`11/3:x=7/6`

`x=11/3:7/6`

`x=11/3xx6/7`

`x=22/7`

17 tháng 8 2023

\(a,x+\dfrac{1}{4}.\dfrac{1}{5}=\dfrac{4}{5}\)

\(\Rightarrow\)\(x+\dfrac{1}{20}=\dfrac{4}{5}\)

\(\Rightarrow x=\dfrac{4}{5}-\dfrac{1}{20}=\dfrac{16}{20}-\dfrac{1}{20}=\dfrac{3}{4}\)

\(b,3\dfrac{2}{3}:x=2\dfrac{2}{3}-1\dfrac{1}{2}\)

\(\Rightarrow\dfrac{11}{3}:x=\dfrac{7}{6}\)

\(\Rightarrow x=\dfrac{11}{3}:\dfrac{7}{6}=\dfrac{22}{7}\)

Bài 1: 

c) ĐKXĐ: \(x\notin\left\{\dfrac{1}{4};-\dfrac{1}{4}\right\}\)

Ta có: \(\dfrac{3}{1-4x}=\dfrac{2}{4x+1}-\dfrac{8+6x}{16x^2-1}\)

\(\Leftrightarrow\dfrac{-3\left(4x+1\right)}{\left(4x-1\right)\left(4x+1\right)}=\dfrac{2\left(4x-1\right)}{\left(4x+1\right)\left(4x-1\right)}-\dfrac{6x+8}{\left(4x-1\right)\left(4x+1\right)}\)

Suy ra: \(-12x-3=8x-2-6x-8\)

\(\Leftrightarrow-12x-3-2x+10=0\)

\(\Leftrightarrow-14x+7=0\)

\(\Leftrightarrow-14x=-7\)

\(\Leftrightarrow x=\dfrac{1}{2}\)(nhận)

Vậy: \(S=\left\{\dfrac{1}{2}\right\}\)

18 tháng 4 2023

a) x - 3/2 = 4/3 

    x = 4/3 + 3/2

    x = 8/6 + 9/6 = 17/6

b) 2/5 * x = 1/3

    x = 1/3 : 2/5

    x = 1/3 x 5/2 = 5/6

c) x - 4/9 = 3/7 : 9/14

    x - 4/9 = 2/3

    x = 2/3 + 4/9

    x = 6/9 + 4/9 = 10/9

d) 3/5 * x - 1/2 = 1/5

    3/5 * x = 1/5 + 1/2 = 7/10

    x = 7/10 : 3/5

    x = 7/10 * 5/3 = 7/6

18 tháng 4 2023

a/\(x-\dfrac{3}{2}=\dfrac{4}{3}\)
\(x=\dfrac{4}{3}+\dfrac{3}{2}\)
\(x=\dfrac{17}{6}\)
b/\(\dfrac{2}{5}\times x=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}:\dfrac{2}{5}\)
\(x=\dfrac{5}{6}\)
c/\(x-\dfrac{4}{9}=\dfrac{3}{7}:\dfrac{9}{14}\)
\(x-\dfrac{4}{9}=\dfrac{2}{3}\)
\(x=\dfrac{2}{3}+\dfrac{4}{9}\)
\(x=\dfrac{10}{9}\)
d/\(\dfrac{3}{5}\times x-\dfrac{1}{2}=\dfrac{1}{5}\)
\(\dfrac{3}{5}\times x=\dfrac{1}{5}+\dfrac{1}{2}\)
\(\dfrac{3}{5}\times x=\dfrac{7}{10}\)
\(x=\dfrac{7}{10}:\dfrac{3}{5}\)
\(x=\dfrac{7}{6}\)

16 tháng 5 2023

rảnh à

 

6 tháng 11 2023

100

25 tháng 7 2021

a) (x-2)3+6(x+1)2-x3+12=0

\(\Rightarrow\)x3-6x2+12x-8+6(x2+2x+1)-x3+12=0

\(\Rightarrow\)x3-6x2+12x-8+6x2+12x+6-x3+12=0

\(\Rightarrow\)24x+10=0

\(\Rightarrow\)24x=-10

\(\Rightarrow\)x=\(\dfrac{-10}{24}=\dfrac{-5}{12}\)

25 tháng 7 2021

b)(x-5)(x+5)-(x+3)2+3(x-2)2=(x+1)2-(x-4)(x+4)+3x2

\(\Rightarrow\)x2-25-(x2+6x+9)+3(x2-4x+4)=x2+2x+1-(x2-16)+3x2

\(\Rightarrow\)x2​-25-x2-6x-9+3x2-12x+12=x2+2x+1-x2+16+3x2

\(\Rightarrow\)3x2-18x-22=3x2+2x+17

\(\Rightarrow\)3x2-18x-22-3x2-2x-17=0

\(\Rightarrow\)-20x-39=0

\(\Rightarrow\)-20x=39

\(\Rightarrow\)x=\(-\dfrac{39}{20}\)

4 tháng 3 2021

a) \(\dfrac{1}{2}+x=\dfrac{5}{6}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{2}=\dfrac{5}{6}-\dfrac{3}{6}=\dfrac{2}{6}=\dfrac{1}{3}\)

b) \(x+\dfrac{1}{4}=\dfrac{3}{4}\)

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

c) \(x-\dfrac{1}{5}=\dfrac{3}{10}\)

\(\Rightarrow x=\dfrac{3}{10}+\dfrac{1}{5}=\dfrac{3}{10}+\dfrac{2}{10}=\dfrac{5}{10}=\dfrac{1}{2}\)

d) \(\dfrac{5}{6}-x=\dfrac{1}{3}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{1}{3}=\dfrac{5}{6}-\dfrac{2}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)

e) \(\dfrac{3}{10}+x=\dfrac{1}{2}\)

\(\Rightarrow x=\dfrac{1}{2}-\dfrac{3}{10}=\dfrac{5}{10}-\dfrac{3}{10}=\dfrac{2}{10}=\dfrac{1}{5}\)

g) \(x+\dfrac{1}{4}=\dfrac{3}{8}\)

\(\Rightarrow x=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{3}{8}-\dfrac{2}{8}=\dfrac{1}{8}\)

4 tháng 3 2021

a) 12+x=5612+x=56

⇒x=56−12=56−36=26=13⇒x=56−12=56−36=26=13

b) x+14=34x+14=34

⇒x=34−14=24=12⇒x=34−14=24=12

c) x−15=310x−15=310

⇒x=310+15=310+210=510=12⇒x=310+15=310+210=510=12

d) 56−x=1356−x=13

⇒x=56−13=56−26=36=12⇒x=56−13=56−26=36=12

e) 310+x=12310+x=12

⇒x=12−310=510−310=210=15⇒x=12−310=510−310=210=15

g) x+14=38x+14=38

⇒x=38−14=38−28=18⇒x=38−14=38−28=18

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