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7 tháng 10 2018

[-5/2]-[-0,25] =5/2-1/4=9/4

hok tốt 

[] là dấu giá trị tuyệt đối

7 tháng 10 2018

con: 13 tuổi

mẹ :40 tuổi

30 tháng 1 2023

Trước hết ta có \(\left(\dfrac{x}{y}\right)^{-z}=\dfrac{1}{\left(\dfrac{x}{y}\right)^z}=\dfrac{1}{\dfrac{x^z}{y^z}}=\dfrac{y^z}{x^z}\)

Suy ra:

\(A=\left(0,25\right)^{-1}\cdot\left(\dfrac{1}{4}\right)^{-2}\cdot\left(\dfrac{4}{3}\right)^{-2}\cdot\left(\dfrac{5}{4}\right)^{-1}\cdot\left(\dfrac{2}{3}\right)^{-3}\)

\(A=\left(\dfrac{1}{4}\right)^{-1}\cdot\left(\dfrac{1}{4}\right)^{-2}\cdot\left(\dfrac{4}{3}\right)^{-2}\cdot\left(\dfrac{5}{4}\right)^{-1}\cdot\left(\dfrac{2}{3}\right)^{-3}\)

\(A=4\cdot4^2\cdot\dfrac{3^2}{4^2}\cdot\dfrac{4}{5}\cdot\dfrac{3^3}{2^3}=4^2\cdot3^5\text{​​}\div5\div2^3\)

\(A=2^4\div2^3\cdot3^5\div5=2\cdot3^5\div5=2\cdot243\div5=\dfrac{486}{5}\)

14 tháng 11 2023

1, (0,25 - \(x\)) : - \(\dfrac{3}{5}\) = - \(\dfrac{3}{4}\)

    0,25 - \(x\)           = - \(\dfrac{3}{4}\) x (- \(\dfrac{3}{5}\))

     0,25 - \(x\)           = \(\dfrac{9}{20}\)

                \(x\)          = 0,25 - 0,45 

                \(x\)          = - 0,2 

 

14 tháng 11 2023

2, - \(\dfrac{3}{8}\)\(x\) - 0,75 = - 1\(\dfrac{1}{2}\)

    - \(\dfrac{3}{8}\)\(x\) - 0,75  = -1,5

       \(\dfrac{3}{8}\)\(x\)             = - 0,75 + 1,5

       \(\dfrac{3}{8}\)\(x\)            =  0,75

          \(x\)            = 0,75 : \(\dfrac{3}{8}\)

          \(x\)           =   2

       

22 tháng 7 2023

\(1,\left[\left(-\dfrac{2}{5}\right)+\dfrac{1}{3}\right]-\left(\dfrac{3}{5}-\dfrac{1}{3}\right)=-\dfrac{2}{5}+\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{1}{3}\\ =\left(-\dfrac{2}{5}-\dfrac{3}{5}\right)+\left(\dfrac{1}{3}+\dfrac{1}{3}\right)\\ =\dfrac{-2-3}{5}+\dfrac{1+1}{3}\\ =-\dfrac{5}{5}+\dfrac{2}{3}\\ =-1+\dfrac{2}{3}\\ =\dfrac{-3+2}{3}=-\dfrac{1}{3}\\ b,\left(\dfrac{3}{2}-\dfrac{3}{4}\right)-\left(0,25+\dfrac{1}{2}\right)\\ =\left(\dfrac{3}{2}-\dfrac{3}{4}\right)-\left(\dfrac{1}{4}+\dfrac{1}{2}\right)\\ =\dfrac{3}{2}-\dfrac{3}{4}-\dfrac{1}{4}-\dfrac{1}{2}\\ =\left(\dfrac{3}{2}-\dfrac{1}{2}\right)+\left(-\dfrac{3}{4}-\dfrac{1}{4}\right)\\ =\dfrac{3-1}{2}+\dfrac{-3-1}{4}\\ =\dfrac{2}{2}-\dfrac{4}{4}=1-1=0\)

1: =-2/5+1/3-3/5+1/3

=-1+2/3=-1/3

2: =3/2-3/4-1/4-1/2

=1-1=0

19 tháng 9 2023

`(2/3-0,25+2)-(2-5/2+1/4)-(2,5-1/3)`

`= 2/3 -1/4 +2-2+ 5/2 -1/4 -5/2 +1/3`

`= (2/3 +1/3) +(-1/4 -1/4) + (2-2) + (5/2-5/2)`

`= 3/3 + (-1/2) + 0 + 0`

`= 1 +(-1/2)`

`= 1/2`

DT
19 tháng 9 2023

\(\left(\dfrac{2}{3}-0,25+2\right)-\left(2-\dfrac{5}{2}+\dfrac{1}{4}\right)-\left(2,5-\dfrac{1}{3}\right)\\ =\dfrac{2}{3}-0,25+2-2+\dfrac{5}{2}-\dfrac{1}{4}-2,5+\dfrac{1}{3}\\ =\left(\dfrac{2}{3}+\dfrac{1}{3}\right)+\left(\dfrac{5}{2}-2,5\right)+\left(2-2\right)+\left(-\dfrac{1}{4}-0,25\right)\\ =\dfrac{3}{3}+\left(2,5-2,5\right)+0+\left(-\dfrac{1}{4}-\dfrac{1}{4}\right)\\ =1+0+0+\left(-\dfrac{1}{2}\right)=\dfrac{1}{2}\)

31 tháng 10 2020

\(a,\frac{1}{3}x+0.25=\frac{5}{7}\)

\(\Leftrightarrow\frac{1}{3}x=\frac{13}{28}\)

\(\Leftrightarrow x=\frac{39}{28}\)

vậy...

\(b,\frac{11}{12}x+0,25=\frac{5}{6}\)

\(\Leftrightarrow\frac{11}{12}x=\frac{7}{12}\)

\(\Leftrightarrow x=\frac{7}{11}\)

vậy.....

\(c,\left(\frac{-1}{3}\right)^2+\frac{2}{3}x=\frac{1}{4}\)

\(\Leftrightarrow\frac{1}{9}+\frac{2}{3}x=\frac{1}{4}\)

\(\Leftrightarrow\frac{2}{3}x=\frac{5}{36}\)

\(\Leftrightarrow x=\frac{5}{24}\)

vậy......

\(d,\left(3x+2\right)^3=-\frac{8}{125}\)

\(\Leftrightarrow3x+2=-\frac{2}{5}\)

\(\Leftrightarrow3x=-\frac{12}{5}\)

\(\Leftrightarrow x=-\frac{4}{5}\)

vậy.......

31 tháng 10 2020

\(\frac{1}{3x}+0,25=\frac{5}{7}\)

\(\frac{1}{3x}+\frac{1}{4}=\frac{5}{7}\)

\(\frac{1}{3x}=\frac{13}{28}\)

\(3x=\frac{28}{13}\)

\(x=\frac{28}{39}\)

\(\frac{11}{12x}+0,25=\frac{5}{6}\)

\(\frac{11}{12x}+\frac{1}{4}=\frac{5}{6}\)

\(\frac{11}{12x}=\frac{7}{12}\)

\(x=\frac{11}{12}:\frac{7}{12}\)

\(x=\frac{7}{11}\)

\(\left(-\frac{1}{3}\right)^2+\frac{2}{3x}=\frac{1}{4}\)

\(\frac{1}{9}+\frac{2}{3x}=\frac{1}{4}\)

\(\frac{2}{3x}=\frac{5}{36}\)

\(x=\frac{2}{3}:\frac{5}{36}\)

\(x=\frac{5}{24}\)

\(\left(3x+2\right)^3=\left(-\frac{8}{125}\right)\)

\(\left(3x+2\right)^3=\left(-\frac{2}{5}\right)^3\)

\(\Rightarrow3x+2=-\frac{2}{3}\)

\(3x=-\frac{8}{3}\)

\(x=-\frac{9}{8}\)

4 tháng 8 2017

a,=11/12 x 8/15 - 1/6:2

  = 22/45-1/2

  = 73/180

b, =9/4:0.01 

   = 225

K nha

4 tháng 8 2017

0,25 x 40

= 10

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