\(\frac{3}{4}\):5

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Bài 2: 

a: =>x/4=1/8

hay x=1/2

b: \(\Leftrightarrow\dfrac{x}{-5}=\dfrac{11}{6}\)

hay x=-55/6

c: \(\Leftrightarrow\dfrac{-3.5}{x}=\dfrac{4.25}{8}\)

hay x=-112/17

29 tháng 8 2018

\(3\frac{1}{3}:x=2\frac{1}{2}:4\frac{5}{6}\)

\(\Rightarrow\frac{10}{3}:x=\frac{5}{2}:\frac{29}{6}\)

\(\Rightarrow\frac{10}{3}:x=\frac{15}{29}\)

\(\Rightarrow x=\frac{10}{3}:\frac{15}{29}\)

\(\Rightarrow x=\frac{58}{9}\)

25 tháng 9 2017

a) \(\frac{x}{7}=\frac{18}{14}\)

\(\frac{x}{7}=\frac{9}{7}\)

\(\Rightarrow x=9\)

b) \(6:x=1\frac{3}{4}:5\)

\(6:x=\frac{7}{4}.\frac{1}{5}\)

\(6:x=\frac{7}{20}\)

\(x=6:\frac{7}{20}\)

\(x=\frac{120}{7}\)

vay \(x=\frac{120}{7}\)

c) \(\frac{5,7}{0,35}=\frac{-x}{0,45}\)

\(\Rightarrow-0,35x=5,7.0,45\)

\(\Rightarrow-0,35x=2,565\)

\(\Rightarrow x=\frac{-2,565}{0,35}\)

\(\Rightarrow x=\frac{-513}{70}\)

vay \(x=\frac{-513}{70}\)

13 tháng 10 2016

he he !! linh học giỏi hơn mình lun !! mình học dở ẹc àk !!

Đại số lớp 7

23 tháng 7 2016

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

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

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

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

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

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

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

\(\Rightarrow x=\frac{35}{12}:\frac{1}{3}=\frac{35}{4}\)

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

\(=15=2,5:\left(0,1\cdot x\right)\)

\(\Rightarrow0,1\cdot x=2,25:15\)

\(\Rightarrow x=\frac{3}{20}:0,1=\frac{3}{2}=1,5\)

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

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

\(\Rightarrow\frac{1}{4}\cdot x=8:100\)

\(\Rightarrow x=\frac{2}{25}:\frac{1}{4}=\frac{8}{25}=0,32\)

d) \(3:2\frac{1}{4}=\frac{3}{4}:\left(6\cdot x\right)\)

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

\(\Rightarrow6\cdot x=\frac{3}{4}:\frac{4}{3}\)

\(\Rightarrow x=\frac{9}{16}:6=\frac{3}{32}=0,09375\)

11 tháng 7 2019

a) \(\frac{x-1}{x+5}=\frac{6}{7}\)

\(\Rightarrow7.\left(x-1\right)=6.\left(x+5\right)\)

\(\Rightarrow7x-7=6x+30\)

\(\Rightarrow7x-6x=7+30\)

\(\Rightarrow x=37\)

b) \(\frac{x^2}{6}=\frac{24}{25}\)

\(\Rightarrow25.x^2=24.6\)

\(\Rightarrow25.x^2=144\)

\(\Rightarrow x^2=144:25\)

\(\Rightarrow x^2=\frac{144}{25}\)

\(\Rightarrow x^2=\frac{12^2}{5^2}\)

\(\Rightarrow x^2=\frac{12}{5}^2\)

\(\Rightarrow x=\pm\frac{12}{5}\)

11 tháng 7 2019

\(c,\frac{x-2}{x-1}=\frac{x+4}{x+7}\)

\(\Leftrightarrow(x-2)(x+7)=(x+4)(x-1)\)

\(\Leftrightarrow x^2+5x-14=x^2+3x-4\)

\(\Leftrightarrow x^2+5x-14-x^2+3x=-4\)

\(\Leftrightarrow\left[x^2-x^2\right]+5x-3x-14=-4\)

\(\Leftrightarrow2x-14=-4\)

\(\Leftrightarrow2x=10\Leftrightarrow x=5\)

10 tháng 7 2016

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 \(x=\frac{100}{9}\)

10 tháng 7 2016

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