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Chỗ 1/3/4 í

Sửa lại nhé

$-\dfrac{3}{x-2} = \dfrac45$

$4(x-2) = (-3).5$

$4x - 8 = -15$

$x = -\dfrac74$

\(\dfrac{-3}{x-2}=\dfrac{4}{5}\\ =>\left(x-2\right)\cdot4=-3\cdot5\\ =>\left(x-2\right)\cdot4=-15\\ =>x-2=-15:4\\ =>x-2=-3,75\\ =>x=-3,75+2\\ =>x=-1,75\)

a) \(\frac{3x-2}{1\frac{2}{5}}=\frac{2\frac{3}{7}}{2\frac{3}{5}}\Rightarrow3x-2=1.\frac{2}{5}.\frac{2\frac{3}{7}}{2\frac{3}{5}}=\frac{7}{5}.\frac{17}{7}.\frac{5}{13}\)

\(3x-2=\frac{17}{13}\Rightarrow3x=2+\frac{17}{13}=\frac{43}{13}\Rightarrow x=\frac{43}{39}.\)

b) \(\frac{x}{0,16}=\frac{9}{x}\Rightarrow x^2=9.0,16=1,44\Rightarrow x=\pm1,2\)

Lời giải:

a.

$x:27=-2:3,6=\frac{-5}{9}$

$x=27.\frac{-5}{9}=-15$

b.

$\frac{2x+1}{-27}=\frac{-3}{2x+1}$

$\Rightarrow (2x+1)^2=(-27)(-3)=81=9^2=(-9)^2$

$\Rightarrow 2x+1=9$ hoặc $2x+1=-9$

$\Rightarrow x=4$ hoặc $x=-5$

2:

a: Áp dụng tính chất của DTSBN, ta được:

a/5=b/-2=(a+b)/(5-2)=12/3=4

=>a=20; b=-8

b: Áp dụng tính chất của DTSBN, ta được:

a/4=b/5=(3a-2b)/(3*4-2*5)=42/2=21

=>a=84; b=105

\(a,\left(\frac{1}{3}.x\right):\frac{2}{3}=1\frac{3}{4}:\frac{2}{5}\)

    \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{35}{8}\)

\(\frac{1}{3}x\div\frac{2}{3}=\frac{13}{4}\div\frac{2}{5}\)

\(\frac{1}{2}x=\frac{65}{8}\)

\(x=\frac{65}{4}\)

Mình ko chắc chắn nhé

 thiếu nha

  tiếp nè

(1/3.x)=35/8:2/5

(1/3.x)=175/16

      x=175/16:1/3

x=525/16

a) \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{7}{4}:\frac{2}{5}\)

\(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{35}{8}\)

\(\Rightarrow\frac{1}{3}.x=\frac{35}{8}.\frac{2}{3}\)

\(\Rightarrow\frac{1}{3}.x=\frac{35}{12}\)

\(\Rightarrow x=\frac{35}{12}:\frac{1}{3}\)

\(\Rightarrow x=\frac{35}{4}\)

Vậy \(x=\frac{35}{4}\)

a) x= \(\frac{35}{4}\)

\(a.\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{7}{4}:\frac{2}{5}\)

    \(\left(\frac{1}{3}.x\right):\frac{2}{3}=\frac{35}{8}\)

          \(\left(\frac{1}{3}.x\right)=\frac{35}{8}.\frac{2}{3}\)

          \(\left(\frac{1}{3}.x\right)=\frac{35}{12}\)

                    \(x=\frac{35}{12}:\frac{1}{3}\)

                    \(x=\frac{35}{4}\)

\(b.4,5:0,3=2,25:\left(0,1.x\right)\)

\(\Rightarrow2,25:\left(0,1.x\right)=4,5:0,3\)

     \(2,25:\left(0,1.x\right)=15\)

     \(2,25:\left(0,1.x\right)=2,25:15\)

                \(\left(0,1.x\right)=0,15\)

                          \(x=0,15:0,1\)

                          \(x=1,5\)

\(c.8:\left(\frac{1}{4}.x\right)=2:0,02\)

   \(8:\left(\frac{1}{4}.x\right)=100\)

        \(\left(\frac{1}{4}.x\right)=8:100\)

        \(\left(\frac{1}{4}.x\right)=\frac{2}{25}\)

                  \(x=\frac{2}{25}:\frac{1}{4}\)

                  \(x=\frac{8}{25}\)

\(d.3:\frac{9}{4}=\frac{3}{4}:\left(6.x\right)\)

\(\Rightarrow\frac{3}{4}:\left(6.x\right)=3:\frac{9}{4}\)

     \(\frac{3}{4}:\left(6.x\right)=\frac{4}{3}\)

           \(\left(6.x\right)=\frac{3}{4}:\frac{4}{3}\)

          \(\left(6.x\right)=\frac{9}{16}\)

                \(x=\frac{9}{16}:6\)

                \(x=\frac{3}{32}\)

 ^...^ ^_^