tỉ số phần trăm giữa 75000 và 85000 là :

75000:85000=0,8823...

0,8823=88,23%

a) 1/2 : x - 5/6 = -2/3

     1/2 : x        = -2/3 + 5/6

     1/2 : x        = -4/6 + 5/6

     1/2 : x        = 1/6

             x        = 1/2: 1/6

             x        = 3

b) 20% . x + 5/8 - x . 0,5 = 11/20

    1/5   . x  + 5/8 - x . 1/2 = 11/20

     x . (1/5 + 5/8) - 1/2      = 11/20

     x . 33/40 - 1/2              = 11/20

     x . 13/40                      = 11/20 

     x                                   = 11/20 : 13/40

     x                                  = 22/13

c) chịu

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Lấy 28 viên bi nkaa

\(3\cdot\left(3x-\dfrac{1}{2}\right)^3+\dfrac{1}{9}=0\)

\(\Rightarrow3\cdot\left(3x-\dfrac{1}{2}\right)^3=-\dfrac{1}{9}\)

\(\Rightarrow\left(3x-\dfrac{1}{2}\right)^3=-\dfrac{1}{9}:3\)

\(\Rightarrow \left(3x-\dfrac{1}{2}\right)^3=-\dfrac{1}{27}\)

\(\Rightarrow\left(3x-\dfrac{1}{2}\right)^3=\left(-\dfrac{1}{3}\right)^3\)

\(\Rightarrow3x-\dfrac{1}{2}=-\dfrac{1}{3}\)

\(\Rightarrow3x=-\dfrac{1}{3}+\dfrac{1}{2}\)

\(\Rightarrow3x=\dfrac{1}{6}\)

\(\Rightarrow x=\dfrac{1}{6}:3=\dfrac{1}{18}\)

\(x+\dfrac{13}{15}=-\dfrac{2}{5}\\ x=-\dfrac{2}{5}-\dfrac{13}{15}\\ x=-\dfrac{6}{15}-\dfrac{13}{15}\\ x=-\dfrac{19}{15}\)

`3/4 + 1/4 : x = -3`

`=> 1/4 : x = -3 - 3/4`

`=> 1/4 : x = -12/4 - 3/4`

`=> 1/4 : x = -15/4`

`=> x = 1/4 : (-15/4)`

`=> x =1/4 . (-4)/15`

`=> x = -1/15`

Vậy: `x = -1/15`

Ta thấy :

\(\dfrac{3}{10}>\dfrac{3}{15}\)

\(\dfrac{3}{11}>\dfrac{3}{15}\)

\(\dfrac{3}{12}>\dfrac{3}{15}\)

\(\dfrac{3}{13}>\dfrac{3}{15}\)

\(\dfrac{3}{14}>\dfrac{3}{15}\)

\(\Rightarrow S=\dfrac{3}{10}+\dfrac{3}{11}+\dfrac{3}{12}+\dfrac{3}{13}+\dfrac{3}{14}>5.\dfrac{3}{15}\) (1)

\(S=\dfrac{3}{10}+\dfrac{3}{11}+\dfrac{3}{12}+\dfrac{3}{13}+\dfrac{1}{14}>1\)

Ta có:

\(\dfrac{3}{10}< \dfrac{3}{9}\)

\(\dfrac{3}{11}< \dfrac{3}{9}\)

\(\dfrac{3}{12}< \dfrac{3}{9}\)

\(\dfrac{3}{13}< \dfrac{3}{9}\)

\(\dfrac{3}{14}< \dfrac{3}{9}\)

\(\Rightarrow S=\dfrac{3}{10}+\dfrac{3}{11}+\dfrac{3}{12}+\dfrac{3}{13}+\dfrac{3}{14}< 5.\dfrac{3}{9}\)

\(\Rightarrow S< \dfrac{5}{3}< 2\)

giải s ta có s=1.267782218 thì lớn hơn 1 và nhỏ hơn 2 

cíu mik vs mik đang cần gấp

  \(-\dfrac{1}{12}\) < \(\dfrac{x}{24}\) < \(\dfrac{1}{8}\)

  - \(\dfrac{2}{24}\) < \(\dfrac{x}{24}\) < \(\dfrac{3}{24}\)

- 2 < \(x\) < 3

  \(x\) \(\in\) {-1; 0; 1; 2}

Vậy \(x\) \(\in\) {-1; 0; 1; 2}

35%\(x\) + 0,5\(x\) + \(x\): 2 = 27

   \(x\) \(\times\) 0,35 + \(x\) \(\times\) 0,5 + \(x\) \(\times\) 0,5 = 27

  \(x\) \(\times\) (0,35 + 0,5 + 0,5) = 27

  \(x\) \(\times\) 1,35 = 27

 \(x\)              = 27 : 1,35

\(x\)               = 20

Vậy \(x\) = 20

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