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31 tháng 1 2016

-12x-(-12.5)+(7.3-7x)=-141

-12x+60+21-7x=-141

(-12x-7x)=-141-60-21

-19x=-222

x=-222:(-19)

x=222/19

b: =>x(8-7)=-33

=>x=-33

c: =>-12x+60+21-7x=5

=>-19x=-76

hay x=4

d: =>-2x-2-x+5+2x=0

=>3-x=0

hay x=3

9 tháng 1 2018

***c,4(x-5)-3(x+7)=-19

Suy ra (4x-20)-(3x+21)=-19

Suy ra (4x-3x)-(20+21)=-19

Suy ra x-41=-19

suy ra x=-19+41

Suy ra x=22

Vậy x=22

a: x*3/4=1/5

=>x=1/5:3/4=1/5*4/3=4/15

b: x*3/7=2/5

=>x=2/5:3/7=2/5*7/3=14/15

c: 1/3+2/9=2/12x

=>1/6x=3/9+2/9=5/9

=>x=5/9*6=30/9=10/3

d: 4/15*x-2/3=1/5

=>4/15*x=2/3+1/5=10/15+3/15=13/15

=>4x=13

=>x=13/4

e: x:1/7=2/3

=>x=2/3*1/7=2/21

f: 1/9:x=7/3

=>x=1/9:7/3=1/9*3/7=3/63=1/21

j: 1/4+5/12=8/3:x

=>8/3:x=3/12+5/12=8/12=2/3

=>x=4

h: =>7/4:x=1/5+1/2=7/10

=>x=7/4:7/10=10/4=5/2

30 tháng 8 2023

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31 tháng 12 2016

Bài 1:
\(\frac{\frac{5}{131}+\frac{5}{141}-\frac{5}{191}-\frac{5}{4011}}{\frac{7}{131}+\frac{7}{141}+\frac{7}{-191}-\frac{7}{4011}}=\frac{5\left(\frac{1}{131}+\frac{1}{141}-\frac{1}{191}-\frac{1}{4011}\right)}{7\left(\frac{1}{131}+\frac{1}{141}-\frac{1}{191}-\frac{1}{4011}\right)}=\frac{5}{7}\)

Bài 2:
a) \(\frac{x}{7}+\left(\frac{-3}{7}\right)^2=\frac{2}{7}:\frac{4}{3}\)

\(\Rightarrow\frac{x}{7}+\frac{9}{49}=\frac{3}{14}\)

\(\Rightarrow\frac{x}{7}=\frac{3}{98}\)

\(\Rightarrow98x=21\)

\(\Rightarrow x=\frac{3}{14}\)

Vậy \(x=\frac{3}{14}\)

b) \(\left(x-1\right)^{x+6}=\left(x-1\right)^{x+4}\)

\(\Rightarrow\left(x-1\right)^{x+6}-\left(x-1\right)^{x+4}=0\)

\(\Rightarrow\left(x-1\right)^{x+4}.\left[\left(x-1\right)^2-1\right]=0\)

\(\Rightarrow\left(x-1\right)^{x+1}=0\) hoặc \(\left(x-1\right)^2-1=0\)

+) \(\left(x-1\right)^{x+1}=0\Rightarrow x-1=0\Rightarrow x=1\)

+) \(\left(x-1\right)^2-1=0\)

\(\Rightarrow\left(x-1\right)^2=1\)

\(\Rightarrow\left(x-1\right)=\pm1\)

+ \(x-1=1\Rightarrow x=2\)

+ \(x-1=-1\Rightarrow x=0\)

Vậy \(x\in\left\{0;2;1\right\}\)

31 tháng 12 2016

1)

\(\frac{\frac{5}{131}+\frac{5}{141}-\frac{5}{191}-\frac{5}{4011}}{\frac{7}{131}+\frac{7}{141}+\frac{7}{-191}-\frac{7}{4011}}\)

\(=\frac{5\left(\frac{1}{131}+\frac{1}{141}-\frac{1}{191}-\frac{1}{4011}\right)}{7\left(\frac{1}{131}+\frac{1}{141}-\frac{1}{191}-\frac{1}{4011}\right)}\)

\(=\frac{5}{7}\)

2) \(\frac{x}{7}+\left(-\frac{3}{7}\right)^2=\frac{2}{7}:\frac{4}{3}\)

\(=\frac{x}{7}+\frac{9}{49}=\frac{3}{14}\)

\(=\frac{x}{7}=\frac{3}{14}-\frac{9}{49}=\frac{3}{98}\)

\(\Rightarrow98x=21\)

\(\Rightarrow x=\frac{3}{14}\)

7 tháng 8 2023

Bài 1:

a) \(\dfrac{9}{20}-\dfrac{8}{15}\times\dfrac{5}{12}\)

\(=\dfrac{9}{20}-\dfrac{2}{9}\)

\(=\dfrac{41}{180}\)

b) \(\dfrac{2}{3}\div\dfrac{4}{5}\div\dfrac{7}{12}\)

\(=\dfrac{2}{3}\times\dfrac{5}{4}\times\dfrac{12}{7}\)

\(=\dfrac{5}{6}\times\dfrac{12}{7}\)

\(=\dfrac{10}{7}\)

c) \(\dfrac{7}{9}\times\dfrac{1}{3}+\dfrac{7}{9}\times\dfrac{2}{3}\)

\(=\dfrac{7}{9}\times\left(\dfrac{1}{3}+\dfrac{2}{3}\right)\)

\(=\dfrac{7}{9}\times1\)

\(=\dfrac{7}{9}\)

 

7 tháng 8 2023

Bài 2:

a) \(2\times\left(x-1\right)=4026\)

\(\left(x-1\right)=4026\div2\)

\(x-1=2013\)

\(x=2014\)

Vậy: \(x=2014\)

b) \(x\times3,7+6,3\times x=320\)

\(x\times\left(3,7+6,3\right)=320\)

\(x\times10=320\)

\(x=320\div10\)

\(x=32\)

Vậy: \(x=32\)

c) \(0,25\times3< 3< 1,02\)

\(\Leftrightarrow0,75< 3< 1,02\) ( S )

=> \(0,75< 1,02< 3\)

26 tháng 5 2017

x : 5 = 141

x = 141 x 5

x = 705

12 tháng 11 2021

\(x=181:11=7\)