a) Lm r nkoa!

b) \(\left(0,25x\right):3=\frac{5}{6}:0,125\)

\(=\left(0,25x\right):3=\frac{20}{3}\)

\(\Rightarrow0,25x=\frac{20}{3}\cdot3=20\)

\(\Rightarrow x=20:0,25=80\)

\(\Rightarrow x=80\)

c) \(0,01:2,5=\left(0,75x\right):0,75\)

\(=\frac{1}{250}=\left(0,75x\right):0,75\)

\(\Rightarrow0,75x=\frac{1}{250}\cdot0,75=\frac{3}{1000}\)

\(\Rightarrow x=\frac{3}{1000}:0,75=\frac{1}{250}\)

\(\Rightarrow x=\frac{1}{250}\)

d) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)

\(=\frac{5}{3}=\frac{2}{3}:\left(0,1x\right)\)

\(\Rightarrow0,1x=\frac{2}{3}:\frac{5}{3}=\frac{2}{5}\)

\(\Rightarrow x=\frac{2}{5}:0,1=4\)

\(\Rightarrow4\)

a)\(3,8:\left(2x\right)=\dfrac{1}{4}:2\dfrac{2}{3}\)

\(2x=3,8:\dfrac{3}{32}\)

\(x=\dfrac{608}{15}:2\)

\(x=\dfrac{304}{15}\)

b)\(\left(0,25x\right):3=\dfrac{5}{6}:0,125\)

\(0,25x=\dfrac{20}{3}\times3\)

\(x=20:0,25\)

\(x=80\)

c) \(0,01:2,5=\left(0,75\times x\right):0,75\)

\(0,004=0,75\times x:0,75\)

\(0,004=x\times0,75:0,75\)

\(0,004=x\times1\)

\(0,004=x\)

\(\Rightarrow x=0,004\)

d)\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:\left(0,1x\right)\)

\(\dfrac{5}{3}=\dfrac{2}{3}:0,1\times x\)

\(\dfrac{5}{3}=\dfrac{20}{3}\times x\)

\(\Rightarrow x=\dfrac{20}{3}:\dfrac{5}{3}\)

\(x=4\)

a) \(x=20\dfrac{4}{15}.\)

b) \(x=80\)

c) \(x=0,004\)

d) \(x=4.\)

1) a) Ta có: \(\frac{x}{-15}=\frac{-60}{x}\) \(\Rightarrow x^2=\left(-15\right).\left(-60\right)=900\)

                                               \(\Rightarrow x=30\)

b) \(\frac{-2}{x}=\frac{-x}{\frac{8}{25}}\) \(\Rightarrow x.\left(-x\right)=\left(-2\right).\frac{8}{25}\)

                               \(\Rightarrow x.\left(-x\right)=\frac{-16}{25}\)

                                \(\Rightarrow x.\left(-x\right)=\left(\frac{-4}{5}\right).\frac{4}{5}\)

Vậy \(x=\frac{4}{5}\)

2) a) \(3,8: \left(2x\right)=\frac{1}{4}:2\frac{2}{3}\)

\(\Rightarrow3,8: \left(2x\right)=\frac{3}{32}\)

\(\Rightarrow2x=\frac{3}{32}:3,8=\frac{15}{608}\)

\(x=\frac{15}{608}:2=\frac{15}{1216}\)

Vậy \(x=\frac{15}{1216}\)

b) \(\left(0,25x\right):3=\frac{5}{6}:0,125\)

\(\Rightarrow\left(0,25x\right):3=\frac{20}{3}\)

\(\Rightarrow0,25x=\frac{20}{3}.3=20\)

\(\Rightarrow x=20:0,25=80\)

Vậy x = 80

c) \(0,01:2,5=\left(0,75x\right):0,75\)

\(\Rightarrow\frac{1}{250}=\left(0,75x\right):0,75\)

\(\Leftrightarrow0,75x=\frac{1}{250}.0,75=\frac{3}{1000}\)

\(\Rightarrow x=\frac{3}{1000}:0,75=\frac{1}{250}\)

Vậy \(x=\frac{1}{250}\)

d) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)

\(\Rightarrow\frac{5}{3}=\frac{2}{3}:\left(0,1x\right)\)

\(\Rightarrow0,1x=\frac{5}{3}.\frac{2}{3}=\frac{10}{9}\)

\(\Rightarrow x=\frac{10}{9}:0,1=\frac{100}{9}\)

Vậy \(x=\frac{100}{9}\)

a) \(\frac{x}{-15}=\frac{-60}{x}\Leftrightarrow x.x=-15.\left(-60\right)\Leftrightarrow x^2=900\Leftrightarrow x^2=\orbr{\begin{cases}30^2\\\left(-30\right)^2\end{cases}}\Leftrightarrow x=\orbr{\begin{cases}30\\-30\end{cases}}\)

3)  \(\frac{x}{4}=\frac{y}{7}\Leftrightarrow\frac{x^2}{4}=\frac{xy}{7}\Leftrightarrow\frac{x^2}{4}=\frac{112}{7}\Leftrightarrow x^2=\frac{448}{7}=64\Leftrightarrow x=\orbr{\begin{cases}8\\-8\end{cases}}\)                                                             \(\Rightarrow y=\orbr{\begin{cases}112:8=14\\112:\left(-8\right)=-14\end{cases}}\)

Giữ lời hứa nka Nguyễn Mạnh Tân!

làm nhanh mình k cho

Hứa k r lm cko! Bài dài lắm

( 0,25x ) : 3 = 5/6 : 0,125

( 1/4x ) : 3 = 5/6 : 1/8

( 1/4x ) : 3 = 5/6 x 8

( 1/4x ) : 3 = 20/3

1/4x          = 20/3 x 3

1/4x         = 20

x              = 20 : 1/4

x              = 80

0,01 : 2,5 = ( 0,75x ) : 0,75

1/100 : 25/10 = (3/4x) : 3/4

1/100 x 10/25 = (3/4x) : 3/4

=>(3/4x) : 3/4 = 1/250

3/4x                = 1/250 x 3/4

3/4x                = 3/1000

x                     = 3/1000 : 3/4

x                     = 1/250

 4/3 : 0,8 = 2/3 : ( 0,1x )

<=>2/3 : (0,1x) = 4/3 : 0,8

2/3 : (0,1x) = 4/3 : 4/5

2/3 : (0,1x) = 4/3 x 5/4

2/3 : (0,1x) = 5/3

2/3 : (1/10x) = 5/3

1/10x           = 2/3 : 5/3

1/10x           = 2/3 x 3/5

1/10x           = 2/5

x                  = 2/5 : 1/10

x                  = 2/5 x 10

x                  = 4

\(a,3,8:2x=\frac{1}{4}:2\frac{2}{3}\)

\(\Leftrightarrow3,8:2x=\frac{3}{32}\)

\(\Leftrightarrow2x=3,8:\frac{3}{32}\)

\(\Leftrightarrow2x=\frac{608}{15}\)

\(\Leftrightarrow x=\frac{304}{15}\)

\(b,0,25x:3=\frac{5}{6}:0,125\)

\(\Leftrightarrow0,25x:3=\frac{20}{3}\)

\(\Leftrightarrow0,25x=20\)

\(\Leftrightarrow x=80\)

\(c,0,01:2,5=0,75x:0,75\)

\(\Leftrightarrow0,75x:0,75=\frac{1}{250}\)

\(\Leftrightarrow x=\frac{1}{250}\)

Mik lm hơi tắt chỗ nào chw hiểu thì hỏi mik nhé

c) (0.01):2,5=(0,75x).(0,75)

         0,004 =(0,75x).(0,75)

         => x=0.0071

Đề này bn xem lại coi có đúng k