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28 tháng 3 2020

Ta có : \(\frac{x-1}{12}-\frac{2x-12}{14}=\frac{3x-14}{25}-\frac{4x-25}{27}\)

=> \(\frac{x-1}{12}-1-\frac{2x-12}{14}-1=\frac{3x-14}{25}-1-\frac{4x-25}{27}-1\)

=> \(\frac{x-13}{12}-\frac{2x-26}{14}=\frac{3x-39}{25}-\frac{4x-52}{27}\)

=> \(\frac{x-13}{12}-\frac{2\left(x-13\right)}{14}=\frac{3\left(x-13\right)}{25}-\frac{4\left(x-13\right)}{27}\)

=> \(\frac{x-13}{12}-\frac{2\left(x-13\right)}{14}-\frac{3\left(x-13\right)}{25}+\frac{4\left(x-13\right)}{27}=0\)

=> \(\left(x-13\right)\left(\frac{1}{12}-\frac{2}{14}-\frac{3}{25}+\frac{4}{27}\right)=0\)

=> \(x-13=0\)

=> \(x=13\)

Vậy phương trình trên có nghiệm là \(S=\left\{13\right\}\)

23 tháng 3 2020

a, \(\frac{x-5}{2015}+\frac{x-4}{2016}=\frac{x-3}{2017}+\frac{x-2}{2018}\)

<=>\(\frac{x-2020}{2015}+\frac{x-2020}{2016}-\frac{x-2020}{2017}-\frac{x-2020}{2018}=0\)

<=> \((x-2020)(\frac{1}{2015}+\frac{1}{2016}-\frac{1}{2017}-\frac{1}{2018})=0\)

<=>\(x-2020=0\)

<=> \(x=2020\)

Vậy_

b, tương tự

4 tháng 2 2017

Phương trình 1:
\(\frac{x-85}{15}+\frac{x-74}{13}+\frac{x-67}{11}+\frac{x-64}{9}=10\)
\(\Rightarrow\frac{x-85}{15}+\frac{x-74}{13}+\frac{x-67}{11}+\frac{x-64}{9}-10=0\)
\(\Rightarrow\left(\frac{x-85}{15}-1\right)+\left(\frac{x-74}{13}-2\right)+\left(\frac{x-67}{11}-3\right)+\left(\frac{x-64}{9}-4\right)=0\)
\(\Rightarrow\frac{x-85-15}{15}+\frac{x-74-26}{13}+\frac{x-67-33}{11}+\frac{x-64-36}{9}=0\)
\(\Rightarrow\frac{x-100}{15}+\frac{x-100}{13}+\frac{x-100}{11}+\frac{x-100}{9}=0\)
\(\Rightarrow\left(x-100\right)\left(\frac{1}{15}+\frac{1}{13}+\frac{1}{11}+\frac{1}{9}\right)=0\)
Do \(\frac{1}{15}+\frac{1}{13}+\frac{1}{11}+\frac{1}{9}\ne0\)
\(\Rightarrow x-100=0\)
\(\Rightarrow x=100\)
Vậy x = 100.

4 tháng 2 2017

Phương trình 3:
\(\frac{1909-x}{91}+\frac{1907-x}{93}+\frac{1905-x}{95}+\frac{1903-x}{97}+4=0\)
\(\Rightarrow\left(\frac{1909-x}{91}+1\right)+\left(\frac{1907-x}{93}+1\right)+\left(\frac{1905-x}{95}+1\right)+\left(\frac{1903-x}{97}+1\right)=0\)
\(\Rightarrow\frac{1909-x+91}{91}+\frac{1907-x+93}{93}+\frac{1905-x+95}{95}+\frac{1903-x+97}{97}=0\)
\(\Rightarrow\frac{2000-x}{91}+\frac{2000-x}{93}+\frac{2000-x}{95}+\frac{2000-x}{97}=0\)
\(\Rightarrow\left(2000-x\right)\left(\frac{1}{91}+\frac{1}{93}+\frac{1}{95}+\frac{1}{97}\right)=0\)
Do \(\frac{1}{91}+\frac{1}{93}+\frac{1}{95}+\frac{1}{97}\ne0\)
\(\Rightarrow2000-x=0\)
\(\Rightarrow x=2000\)
Vậy x = 2000.

5 tháng 6 2019

#)Giải :

a) x + 2x + 3x + ... + 100x = - 213

=> 100x + ( 2 + 3 + 4 + ... + 100 ) = - 213 

=> 100x + 5049 = - 213 

<=> 100x = - 5262

<=> x = - 52,62

5 tháng 6 2019

#)Giải :

b) \(\frac{1}{2}x-\frac{1}{3}=\frac{1}{4}x-\frac{1}{6}\)

\(\Rightarrow\frac{1}{2}x+\frac{1}{4}x=\frac{1}{3}+\frac{1}{6}\)

\(\Rightarrow\frac{1}{2}x+\frac{1}{4}x=\frac{1}{2}\)

\(\Rightarrow\left(\frac{1}{2}+\frac{1}{4}\right)x=\frac{1}{2}\)

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

\(\Leftrightarrow x=\frac{2}{3}\)

4 tháng 10 2021

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