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28 tháng 6 2017

\(\left(85\dfrac{7}{30}-83\dfrac{5}{18}\right):2\dfrac{2}{3}=0,01x:4\)

\(\Leftrightarrow[\left(85-83\right)+\left(\dfrac{7}{30}-\dfrac{5}{18}\right)]:2\dfrac{2}{3}=0,01x:4\)

\(\Leftrightarrow1\dfrac{43}{45}:2\dfrac{2}{3}=0,01x:4\)

\(\Leftrightarrow\dfrac{88}{45}:\dfrac{8}{3}=0,01x:4\)

\(\Leftrightarrow\dfrac{88}{45}.\dfrac{3}{8}=0,01x:4\)

\(\Leftrightarrow\dfrac{11}{15}=0,01x:4\)

\(\Leftrightarrow0,01x:4=\dfrac{11}{15}\)

\(\Leftrightarrow x=\dfrac{11}{15}.4:0,01\)

\(\Leftrightarrow x=\dfrac{880}{3}\)

Vậy x = \(\dfrac{880}{3}\)

8 tháng 7 2018

Ta có:

\(\left(85\dfrac{7}{30}-83\dfrac{5}{18}\right):2\dfrac{2}{3}=0.01x:4\\ \left(\left(85-83\right)+\left(\dfrac{7}{30}-\dfrac{5}{18}\right)\right):\dfrac{8}{3}=0.01x:4\\ \dfrac{88}{45}:\dfrac{8}{3}=0.01x:4\\ \dfrac{11}{15}=0.01x:4\\ \dfrac{44}{15}=0.01x\\ x=\dfrac{44}{15}:0.01\\ x=\dfrac{880}{3}\)

Vậy \(x=\dfrac{880}{3}\)

b: \(\left[\left(6+\dfrac{3}{5}-3-\dfrac{3}{14}\right)\cdot\dfrac{2}{5}\right]:\left(21-1.25\right)=x:\left(5+\dfrac{5}{6}\right)\)

\(\Leftrightarrow x:\dfrac{35}{6}=\dfrac{237}{175}:\dfrac{79}{4}\)

\(\Leftrightarrow x:\dfrac{35}{6}=\dfrac{12}{175}\)

\(\Leftrightarrow x=\dfrac{2}{5}\)

7 tháng 12 2017

?????????????? là sao

1: \(\Leftrightarrow\left(\dfrac{x+1}{85}+1\right)+\left(\dfrac{x+3}{83}+1\right)=\left(\dfrac{x+5}{81}+1\right)+\left(\dfrac{x+7}{79}+1\right)\)

=>x+86=0

=>x=-86

2: \(\Leftrightarrow\left(\dfrac{x-1}{2015}+1\right)-\left(\dfrac{x+3}{2011}+1\right)=\left(\dfrac{x+7}{2007}+1\right)-\left(\dfrac{x+11}{2003}+1\right)\)

=>x+2014=0

=>x=-2014

3: \(\Leftrightarrow3\left(x+4\right)-2\left(x-3\right)=4x\)

=>4x=3x+12-2x+6

=>4x=x+18

=>3x=18

=>x=6

4: \(\Leftrightarrow15x-5\left(x+1\right)=3\left(2x+1\right)\)

=>15x-5x-5=6x+3

=>10x-5=6x+3

=>4x=8

=>x=2

5: \(\Leftrightarrow2\left(2x-7\right)+5\left(x+11\right)=-40\)

=>4x-14+5x+55=-40

=>9x+41=-40

=>x=-9

2 tháng 2 2023

em c.ơn nhiều lắm ạ

Bài 1: 

a: \(A=\dfrac{\left(85+\dfrac{7}{30}-83-\dfrac{5}{18}\right):\dfrac{8}{3}}{\dfrac{1}{25}}\)

\(=\left(2+\dfrac{7}{30}-\dfrac{5}{18}\right)\cdot\dfrac{3}{8}\cdot25\)

\(=\dfrac{180+21-25}{90}\cdot\dfrac{75}{8}\)

\(=\dfrac{176}{90}\cdot\dfrac{75}{8}=\dfrac{55}{3}\)

=>12,5% của A là 55/8x1/8=55/64

b: \(B=\dfrac{\left(6+\dfrac{3}{5}-3-\dfrac{3}{14}\right)\cdot\dfrac{36}{5}}{19.75:2.5}\)

\(=\dfrac{\left(3+\dfrac{27}{70}\right)\cdot\dfrac{36}{5}}{\dfrac{79}{10}}\)

\(=\dfrac{\dfrac{210+27}{70}\cdot\dfrac{36}{5}}{\dfrac{79}{10}}\)

\(=\dfrac{4266}{175}\cdot\dfrac{10}{79}=\dfrac{108}{35}\)

=>5% là 108/35x1/20=27/175

a: 4/9+3/7=28/63+27/63=55/63

3/4+7/24=18/24+7/24=25/24

1/3+2/9+4/27=9/27+6/27+4/27=19/27

b: 5/6-3/8=20/24-9/24=11/24

7/15-11/30=14/30-11/30=3/30=1/10

2/3+1/6-7/12

=8/12+2/12-7/12

=3/12=1/4

c: 18/25*15/6=15/25*18/6=3*3/5=9/5

30/49:6/7=30/49*7/6=210/294=5/7

1/2*3/4:6/5=3/8*5/6=15/48=5/16

d: 8*3/5:12/5=24/5*5/12=2

4:9/5:10/3=4*5/9*3/10=2/3

10 tháng 3 2021

Câu 1:

\(-\dfrac{5}{7}\cdot\dfrac{7}{-45}=\dfrac{1}{9}\) ; \(-\dfrac{3}{10}\cdot-30=9\) ; \(-12\cdot-\dfrac{2}{36}=\dfrac{2}{3}\)

Caau2;3;4;5,... tự bấm máy tính là ra

 

6 tháng 1

\(\dfrac{-2}{45}:\dfrac{8}{3}=0,01x:4\)

\(0,01x:4=\dfrac{-2}{45}\times\dfrac{3}{8}\)

\(0,01x:4=\dfrac{-6}{360}\)

\(0,01x:4=\dfrac{-1}{60}\)

\(0,01x=\dfrac{-1}{60}\times\dfrac{1}{4}\)

\(0,01x=\dfrac{-1}{240}\)

\(x=\dfrac{-1}{240}:0,01\)

\(x=\dfrac{-1}{240}\times100\)

\(x=\dfrac{-100}{240}=-2,4\)

6 tháng 1

\(\dfrac{-2}{45}:\dfrac{8}{3}=0,01x:4\)

\(\dfrac{-2}{45}\times\dfrac{3}{8}=0,01x:4\)

\(\dfrac{-6}{360}=0,01x:4\)

\(\dfrac{-1}{60}=0,01x:4\)

\(0,01x=\dfrac{-1}{60}\times\dfrac{4}{1}\)

\(0,01x=\dfrac{-4}{60}\)

\(0,01x=\dfrac{-1}{15}\)

\(x=\dfrac{-1}{15}:0,01\)

\(x=\dfrac{-1}{15}\times100\)

\(x=\dfrac{-100}{15}=\dfrac{-20}{3}\)

Vậy \(x=\dfrac{-20}{3}\).

AH
Akai Haruma
Giáo viên
5 tháng 1 2019

Bài 1:
\(\frac{99-x}{101}+\frac{97-x}{103}+\frac{95-x}{105}+\frac{93-x}{107}=-4\)

\(\Leftrightarrow \frac{99-x}{101}+1+\frac{97-x}{103}+1+\frac{95-x}{105}+1+\frac{93-x}{107}+1=0\)

\(\Leftrightarrow \frac{99-x+101}{101}+\frac{97-x+103}{103}+\frac{95-x+105}{105}+\frac{93-x+107}{107}=0\)

\(\Leftrightarrow \frac{200-x}{101}+\frac{200-x}{103}+\frac{200-x}{105}+\frac{200-x}{107}=0\)

\(\Leftrightarrow (200-x)\left(\frac{1}{101}+\frac{1}{103}+\frac{1}{105}+\frac{1}{107}\right)=0\)

\(\frac{1}{101}+\frac{1}{103}+\frac{1}{105}+\frac{1}{107}\neq 0\) nên suy ra \(200-x=0\Rightarrow x=200\)

AH
Akai Haruma
Giáo viên
5 tháng 1 2019

Bài 2:

\(\frac{x+14}{86}+\frac{x+15}{85}+\frac{x+16}{84}+\frac{x+116}{4}=0\)

\(\Leftrightarrow \frac{x+14}{86}+1+\frac{x+15}{85}+1+\frac{x+16}{84}+1+\frac{x+17}{83}+1+\frac{x+116}{4}-4=0\)

\(\Leftrightarrow \frac{x+100}{86}+\frac{x+100}{85}+\frac{x+100}{84}+\frac{x+100}{83}+\frac{x+100}{4}=0\)

\(\Leftrightarrow (x+100)\left(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}\right)=0\)

\(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}\neq 0\). Do đó \(x+100=0\Rightarrow x=-100\)