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28 tháng 11 2017

\(\frac{x-1}{13}+\frac{x-2}{14}+\frac{x-3}{15}+3=0\)

\(\frac{x-1}{13}+1+\frac{x-2}{14}+1+\frac{x-3}{15}+1=0\)

\(\frac{x-1}{13}+\frac{13}{13}+\frac{x-2}{14}+\frac{14}{14}+\frac{x-3}{15}+\frac{15}{15}=0\)

\(\frac{x+12}{13}+\frac{x+12}{14}+\frac{x+12}{15}=0\)

\(\left(x+12\right)\left(\frac{1}{13}+\frac{1}{14}+\frac{1}{15}\right)=0\)

\(x+12=0\)hay \(\frac{1}{13}+\frac{1}{14}+\frac{1}{15}=0\)(vô lý)

=>x+12=0

x=0-12

x=-12

Vậy x=-12

28 tháng 11 2017

\(\frac{x-1}{13}\)+    \(\frac{x-2}{14}\) +  \(\frac{x-3}{15}\)+  3  =  0

=> (\(\frac{x-1}{13}\)+  1 )   +  (\(\frac{x-2}{14}\)+  1)  +  (\(\frac{x-3}{15}\) +  1)  =  0

=>  \(\frac{x+12}{13}\)+  \(\frac{x+12}{14}\)+  \(\frac{x+12}{15}\)=  0

=> (x + 12) . (\(\frac{1}{13}\)+\(\frac{1}{14}\)+  \(\frac{1}{15}\))  = 0

=>(x + 12) . \(\frac{587}{2730}\)= 0

=> x + 12 = 0

=> x = -12

Vậy x = -12

2 tháng 8 2019

a) \(\frac{x+2}{12}+\frac{x+2}{13}=\frac{x+2}{14}+\frac{x+2}{15}\)

\(\Leftrightarrow\frac{x+2}{12}+\frac{x+2}{13}-\frac{x+2}{14}-\frac{x+2}{15}=0\)

\(\Leftrightarrow\left(x+2\right)\left(\frac{1}{12}+\frac{1}{13}-\frac{1}{14}-\frac{1}{15}\right)=0\)

Vì \(\frac{1}{12}+\frac{1}{13}-\frac{1}{14}-\frac{1}{15}>0\)

\(\Rightarrow x+2=0\)

\(\Leftrightarrow x=-2\)

b) \(\frac{x+4}{2016}+\frac{x+3}{2017}=\frac{x+2}{2018}+\frac{x+1}{2019}\)

\(\Leftrightarrow\frac{x+4}{2016}+1+\frac{x+3}{2017}+1=\frac{x+2}{2018}+1+\frac{x+1}{2019}+1\)

\(\Leftrightarrow\frac{x+2020}{2016}+\frac{x+2020}{2017}-\frac{x+2020}{2018}-\frac{x+2020}{2019}=0\)

\(\Leftrightarrow\left(x+2020\right)\left(\frac{1}{2016}+\frac{1}{2017}-\frac{1}{2018}-\frac{1}{2019}\right)=0\)

Vì \(\frac{1}{2016}+\frac{1}{2017}-\frac{1}{2018}-\frac{1}{2019}>0\)

\(\Rightarrow x+2020=0\)

\(\Leftrightarrow x=-2020\)

2 tháng 8 2019

a) \(\left(x+2\right)\left(\frac{1}{12}+\frac{1}{13}-\frac{1}{14}-\frac{1}{15}\right)=0\)

=>\(x+2=0\)

=>\(x=-2\)

nếu có sai thì mong bn thông cảm nha

9 tháng 11 2015

tick rồi mình trả lời cho

9 tháng 11 2015

\(\Leftrightarrow\frac{x+2}{327}+1+\frac{x+3}{326}+1+\frac{x+4}{325}+1+\frac{x+5}{324}+1+\frac{x+324}{5}=0\)

\(\Leftrightarrow\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)

\(\Leftrightarrow\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)=0\)\(Vì\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)\ne0\)

=> x+329=0

=> x = -329

b) \(\Leftrightarrow\left(x+2\right)\left(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}-\frac{1}{14}-\frac{1}{15}\right)=0\)\(Vì\left(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}-\frac{1}{14}-\frac{1}{15}\right)\ne0\)

=> x+2 =0 => x =-2

5 tháng 11 2015

a, \(\frac{x+2}{327}+1+\frac{x+3}{326}+1+\frac{x+4}{325}+1+\frac{x+5}{524}+1+\frac{x+329}{5}+\frac{20}{5}-4=0\)

\(\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)

=> x+329=0  => x= -329

b. tương tụ

c,  x=0, x=4

10 tháng 9 2019

Tại sao lại =0??

a) \(\frac{1}{2}-|\frac{5}{4}-2x|=\frac{1}{3}\Leftrightarrow|\frac{5}{4}-2x|=\frac{1}{2}-\frac{1}{3}=\frac{1}{6}\)

\(\Leftrightarrow\orbr{\begin{cases}\frac{5}{4}-2x=\frac{1}{6}\\\frac{5}{4}-2x=-\frac{1}{6}\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=\frac{5}{4}-\frac{1}{6}=\frac{13}{12}\\2x=\frac{5}{4}+\frac{1}{6}=\frac{17}{12}\end{cases}}}\)

Tự làm nốt và kết luận 

b) \(\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}=\frac{x+1}{13}+\frac{x+1}{14}\)

\(\Leftrightarrow\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}-\frac{x+1}{13}-\frac{x+1}{14}=0\)

\(\Leftrightarrow\left(x+1\right)\left(\frac{1}{10}+\frac{1}{11}+\frac{1}{12}-\frac{1}{13}+\frac{1}{14}\right)=0\)

Vì \(\left(\frac{1}{10}+\frac{1}{11}+\frac{1}{12}-\frac{1}{13}+\frac{1}{14}\right)\ne0\forall x\Rightarrow x+1=0\Leftrightarrow x=-1\)

Vậy ....