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5 tháng 9 2018

Ta có : \(\left[x\cdot\frac{1}{2}+2\right]:\frac{3}{5}+4=9.\)

=>         \(\left[x\cdot\frac{1}{2}+2\right]:\frac{3}{5}=9-4.\)

=>          \(\left[x\cdot\frac{1}{2}+2\right]:\frac{3}{5}=5.\)

=>                       \(x\cdot\frac{1}{2}+2=5\cdot\frac{3}{5}.\)

=>                        \(x\cdot\frac{1}{2}+2=3.\)

=>                                 \(x\cdot\frac{1}{2}=3+2.\)

=>                                 \(x\cdot\frac{1}{2}=5.\)

=>                                         \(x=5:\frac{1}{2}.\)

=>                                         \(x=5\cdot2.\)

=>                                         \(x=10.\)

Vậy x = 10 .

5 tháng 9 2018

a)\(\left[x\times\frac{1}{2}+2\right]:\frac{3}{5}+4=9\)                              b)\(x\times\frac{2}{3}-\frac{1}{5}=\frac{2}{5}+1\)

  \(\left[x\times\frac{1}{2}+2\right]:\frac{3}{5}=9-4\)                                \(x\times\frac{2}{3}-\frac{1}{5}=\frac{7}{5}\)

  \(\left[x\times\frac{1}{2}+2\right]:\frac{3}{5}=5\)                                        \(x\times\frac{2}{3}=\frac{7}{5}+\frac{1}{5}\)

   \(x\times\frac{1}{2}+2=5\times\frac{3}{5}\)                                       \(x\times\frac{2}{3}=\frac{8}{5}\)

   \(x\times\frac{1}{2}+2=3\)                                                 \(x=\frac{8}{5}:\frac{2}{3}\)

   \(x\times\frac{1}{2}=3-2\)                                                \(x=\frac{8}{5}\times\frac{3}{2}\)

  \(x\times\frac{1}{2}=1\)                                                         \(x=\frac{12}{5}\)

  \(x=1:\frac{1}{2}\)

  \(x=2\)

a: \(=\dfrac{5\left(x+2\right)}{10xy^2}\cdot\dfrac{12x}{x+2}=\dfrac{60x}{10xy^2}=\dfrac{6}{y^2}\)

b: \(=\dfrac{x-4}{3x-1}\cdot\dfrac{3\left(3x-1\right)}{\left(x-4\right)\left(x+4\right)}=\dfrac{3}{x+4}\)

c: \(=\dfrac{2\left(2x+1\right)}{\left(x+4\right)^2}\cdot\dfrac{\left(x+4\right)}{3\left(x+3\right)}=\dfrac{2\left(2x+1\right)}{3\left(x+3\right)\left(x+4\right)}\)

d: \(=\dfrac{5\left(x-1\right)}{3\left(x+1\right)}\cdot\dfrac{x+1}{x-1}=\dfrac{5}{3}\)

15 tháng 6 2023

\(\dfrac{2}{5}\times\dfrac{1}{7}+\dfrac{2}{7}\times\dfrac{2}{5}\)

\(=\dfrac{2}{5}\times\left(\dfrac{1}{7}+\dfrac{2}{7}\right)\)

\(=\dfrac{2}{5}\times\dfrac{3}{7}\)

\(=\dfrac{6}{35}\)

\(x+\dfrac{1}{2}\times\dfrac{1}{3}=\dfrac{3}{4}\)

\(x+\dfrac{1}{6}=\dfrac{3}{4}\)

\(x=\dfrac{9}{12}-\dfrac{2}{12}\)

\(x=\dfrac{7}{12}\)

\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times...\times\left(1-\dfrac{1}{2020}\right)+x=\dfrac{1}{2}\)

\(\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times...\times\dfrac{2019}{2020}+x=\dfrac{1}{2}\)

\(\dfrac{1}{2020}+x=\dfrac{1}{2}\)

\(x=\dfrac{1}{2}-\dfrac{1}{2020}\)

\(x=\dfrac{1010}{2020}-\dfrac{1}{2020}\)

\(x=\dfrac{1009}{2020}\)

15 tháng 6 2023

\(\dfrac{2}{5}\times\dfrac{1}{7}+\dfrac{2}{7}\times\dfrac{2}{5}\)

\(=\dfrac{2}{5}\times\left(\dfrac{1}{7}+\dfrac{2}{7}\right)\)

\(=\dfrac{2}{5}\times\dfrac{3}{7}\)

\(=\dfrac{6}{35}\)

\(x+\dfrac{1}{2}\times\dfrac{1}{3}=\dfrac{3}{4}\)

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

\(\Rightarrow\dfrac{3}{4}-x=\dfrac{1}{6}\)

\(\Rightarrow x=\dfrac{3}{4}-\dfrac{1}{6}=\dfrac{7}{12}\)

\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times...\times\left(1-\dfrac{1}{2020}\right)+x=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times...\times\dfrac{2019}{2020}+x=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{1\times2\times3\times4\times...\times2019}{2\times3\times4\times5\times...\times2020}+x=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{1}{2020}+x=\dfrac{1}{2}\)

\(\Rightarrow x=\dfrac{1}{2}-\dfrac{1}{2020}=\dfrac{1009}{2020}\)

4 tháng 10 2018

22 + (x - 3) = 52

4 + (x - 3) = 25

x - 3 = 25 - 4

x - 3 = 21

x = 21 + 3

x = 24

6 tháng 10 2018

22 + ( x - 3 ) = 52

<=> 4 + ( x - 3 ) = 25

<=> x - 3 = 21

<=> x = 24

9x - 2 . 32 = 34

<=>9x - 2 = 34 : 32

<=>9x - 2 = 9

<=>9x = 11

<=> x = 11/9

10x + 22 . 5 = 102

<=> 10x + 4 . 5 = 100

<=> 10x + 4 = 20

<=> 10x = 16

<=> x = 1,6

31 tháng 3 2019

diễn giải ra nhé

14 tháng 5 2022

X x \(\dfrac{3}{4}\)+ X x\(\dfrac{1}{5}\)+ X x \(\dfrac{1}{20}\)+ X= 1000

 

28 tháng 8 2019

1)1/9 x 3x = 2187:81=27

            3x=27:1/9=243=35

            =>x=5

  

28 tháng 8 2019

\(\frac{1}{9}.3^4.3^x=3^7\)

\(\Leftrightarrow3^x=3^7:\frac{1}{9}:3^4=243\)

\(\Leftrightarrow3^x=3^5\)

\(\Leftrightarrow x=5\)

1 tháng 10 2020

1) \(x^3+2x-3\)

\(=\left(x^3-x^2\right)+\left(x^2-x\right)+\left(3x-3\right)\)

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

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

2) \(x^3-6x+4\)

\(=\left(x^3-2x^2\right)+\left(2x^2-4x\right)-\left(2x-4\right)\)

\(=x^2\left(x-2\right)+2x\left(x-2\right)-2\left(x-2\right)\)

\(=\left(x-2\right)\left(x^2+2x-2\right)\)

1 tháng 10 2020

3) \(x^3-2x^2+1\)

\(=\left(x^3-x^2\right)-\left(x^2-x\right)-\left(x-1\right)\)

\(=x^2\left(x-1\right)-x\left(x-1\right)-\left(x-1\right)\)

\(=\left(x-1\right)\left(x^2-x-1\right)\)

4) \(x^3+5x^2-12\)

\(=\left(x^3+2x^2\right)+\left(3x^2+6x\right)-\left(6x+12\right)\)

\(=x^2\left(x+2\right)+3x\left(x+2\right)-6\left(x+2\right)\)

\(=\left(x+2\right)\left(x^2+3x-6\right)\)