x là 3 nhé

nếu bn tk cho mk thì mk sẽ thay hình đại diện cho

Ta có: \(\frac{x-2019}{2018}+\frac{x-2018}{2017}=\frac{x-2017}{2016}+\frac{x-2016}{2015}\)

\(\Leftrightarrow\left(\frac{x-2019}{2018}+1\right)+\left(\frac{x-2018}{2017}+1\right)=\left(\frac{x-2017}{2016}+1\right)+\left(\frac{x-2016}{2015}+1\right)\)

\(\Leftrightarrow\frac{x-1}{2018}+\frac{x-1}{2017}=\frac{x-1}{2016}+\frac{x-1}{2015}\)

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

\(\Leftrightarrow\left(x-1\right)\left(\frac{1}{2018}+\frac{1}{2017}-\frac{1}{2016}-\frac{1}{2015}\right)=0\)

\(\Leftrightarrow x-1=0\)( vì \(\frac{1}{2018}+\frac{1}{2017}-\frac{1}{2016}-\frac{1}{2015}\ne0\))

\(\Leftrightarrow x=1\)

Vạy x=1

\(\dfrac{x-25-124}{2015}\) + \(\dfrac{x-124-2015}{25}\) + \(\dfrac{x-2015-25}{124}\) = 3

\(\dfrac{x-15-124}{2015}\) - 1 + \(\dfrac{x-124-2015}{25}\) - 1 + \(\dfrac{x-2015-25}{124}\) - 1 = 0

\(\dfrac{x-15-124-2015}{2015}\)+\(\dfrac{x-124-2015-25}{25}\)+\(\dfrac{x-2015-25-124}{124}\) = 0

\(\dfrac{x-\left(15+124+2015\right)}{2015}\)+\(\dfrac{x-\left(124+2015+25\right)}{25}\)+\(\dfrac{x-\left(2015+25+124\right)}{124}\) = 0

(\(x\) - 2164).(\(\dfrac{1}{2015}\)+\(\dfrac{1}{25}\)+\(\dfrac{1}{124}\)) = 0

\(x-2164\) = 0

\(x\)              = 2164

x = 4038 - 2019 = 2019

~Học tốt~ 

#ngocyen#

\(\frac{x+2019}{x+2018}=\frac{4038}{4037}\)

\(\Leftrightarrow4037(x+2019)=4038(x+2018)\)

\(\Leftrightarrow4037x+8150703=4038x+8148684\)

\(\Leftrightarrow4037x+8150703-4038x=8148684\)

\(\Leftrightarrow4037x-4038x+8150703=8148684\)

\(\Leftrightarrow-x=-2019\)

\(\Leftrightarrow x=2019\)

ko ghi lại đề 

ta thấy : 2019 - 1 = 2018 

2020 - 2 = 2018 

2021 - 3 = 2018 

2022 - 4 = 2018 

=> x = 2018

thử lại :

2018+1/2019 + 2018+2/2020 = 2018+3/2021 + 2018+4/2022

= 1 + 1 = 1 + 1

2 = 2

2020 - 2 = 2018 
2021 - 3 = 2018 
2022 - 4 = 2018 
=> x = 2018

thây zô mà thử lại

c ) 71 + 260 = \(\frac{x}{x}\)+\(\frac{140}{x}\)+260

    331 = 1 + \(\frac{140}{x}\)+260

    331 = \(\frac{140}{x}\)+261

    331 = 140 : x + 261

    140 : x = 331 - 261

    140 : x = 70

    x = 140 : 70

   x =   2

x =2 nha

Ta có 1+1/2014 +1/x=1/(x+1)+1+1/2013 nên 1/x-1/(x+1)=1/2013-1/(2013+1) nên x=2013

Ta có: \(\frac{1}{x}-\frac{1}{x+1}=\frac{2014}{2013}-\frac{2015}{2014}\)

<=> \(\frac{1}{x\left(x+1\right)}=\frac{2014^2-2015.2013}{2013.2014}=\frac{1}{2013.2014}\)

<=> x(x+1)=2013.2014

=> x=2013

Đáp số: x=2013

\(\frac{1-x}{2015}+\frac{2-x}{1007}+\frac{3-x}{671}=\frac{1992-x}{4}\)

\(\left(\frac{1-x}{2015}+1\right)+\left(\frac{2-x}{1007}+2\right)+\left(\frac{3-x}{671}+3\right)=\frac{1992-x}{4}+6\)

\(\left(\frac{2016-x}{2015}+\frac{2016-x}{1007}+\frac{2016-x}{671}\right)=\frac{2016-x}{4}\)

\(\Leftrightarrow\left(2016×x\right)×\left(\frac{1}{2015}+\frac{1}{1007}+\frac{1}{671}-\frac{1}{4}\right)=0\)

Vì\(\frac{1}{2015}+\frac{1}{1007}+\frac{1}{671}-\frac{1}{4}\ne0\)

\(\Rightarrow2016-x=0\)

\(\Rightarrow x=2016\)

Chúc bạn học tốt!

Trl

-Bạn kia làm đúng rồi !~

Học tốt 

nhé bạn :>

Sửa đề \(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=\frac{2015}{2016}\)

\(\Leftrightarrow\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+..+\frac{2}{x\left(x+1\right)}=\frac{2015}{2016}\)

\(\Leftrightarrow\frac{2}{2.3}+\frac{2}{3.4}+\frac{2}{4.5}+..+\frac{2}{x\left(x+1\right)}=\frac{2015}{2016}\)

\(\Leftrightarrow2\cdot\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{2015}{2016}\)

\(\Leftrightarrow\frac{1}{2}-\frac{1}{x+1}=\frac{2015}{2016}\div2\)

\(\Leftrightarrow\frac{1}{2}-\frac{1}{x+1}=\frac{2015}{4032}\)

\(\Leftrightarrow\frac{1}{x+1}=\frac{1}{2}-\frac{2015}{4032}\Leftrightarrow\frac{1}{x+1}=\frac{1}{4032}\)

\(\Leftrightarrow x+1=4032\Rightarrow x=4031\)