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27 tháng 9 2017

Ta có \(\frac{x+1}{2001}+\frac{x+2}{2002}+\frac{x+3}{2003}+\frac{x+4}{2004}=4\)

\(\Rightarrow\frac{x+1}{2001}+\frac{x+2}{2002}+\frac{x+3}{2003}+\frac{x+4}{2004}-4=0\)

\(\Rightarrow\frac{x+1}{2001}-1+\frac{x+2}{2002}-1+\frac{x+3}{2003}-1+\frac{x+4}{2004}-1=0\)

\(\Rightarrow\frac{x+1-2001}{2001}+\frac{x+2-2002}{2002}+\frac{x+3-2003}{2003}+\frac{x+4-2004}{2004}=0\)

\(\Rightarrow\frac{x-2000}{2001}+\frac{x-2000}{2002}+\frac{x-2000}{2003}+\frac{x-2000}{2004}=0\)

\(\Rightarrow\left(x-2000\right)\left(\frac{1}{2001}+\frac{1}{2002}+\frac{1}{2003}+\frac{1}{2004}\right)=0\)

Ta thấy ngay \(\Rightarrow\frac{1}{2001}+\frac{1}{2002}+\frac{1}{2003}+\frac{1}{2004}\ne0\)

\(\Rightarrow x-2000=0\Rightarrow x=2000.\)

27 tháng 9 2017

\(\frac{x+1}{2001}+\frac{x+2}{2002}+\frac{x+3}{2003}+\frac{x+4}{2004}=4\)

\(\Leftrightarrow\left(\frac{x+1}{2001}-1\right)+\left(\frac{x+2}{2002}-1\right)+\left(\frac{x+3}{2003}-1\right)+\left(\frac{x+4}{2004}-1\right)=0\)

\(\Leftrightarrow\left(\frac{x+1-2001}{2001}\right)+\left(\frac{x+2-2002}{2002}\right)+\left(\frac{x+3-2003}{2003}\right)+\left(\frac{x+4-2004}{2004}\right)=0\)

\(\Leftrightarrow\frac{x-2000}{2001}+\frac{x-2000}{2002}+\frac{x-2000}{2003}+\frac{x-2000}{2004}=0\)

\(\Leftrightarrow\left(x-200\right)\left[\frac{1}{2001}+\frac{1}{2002}+\frac{1}{2003}+\frac{1}{2004}\right]=0\)

\(\Leftrightarrow x-2000=0\)

\(\Leftrightarrow x=2000\)

23 tháng 9 2016

\(\frac{x-1}{2004}+\frac{x-2}{2003}-\frac{x-3}{2002}=\frac{x-4}{2001}\)

=> \(\frac{x-1}{2004}+\frac{x-2}{2003}-\frac{x-3}{2002}-\frac{x-4}{2001}=0\)

=> \(\left(\frac{x-1}{2004}-1\right)+\left(\frac{x-2}{2003}-1\right)-\left(\frac{x-3}{2002}-1\right)-\left(\frac{x-4}{2001}-1\right)=0\)

=> \(\frac{x-2005}{2004}+\frac{x-2005}{2003}-\frac{x-2005}{2002}-\frac{x-2005}{2001}=0\)

=> \(\left(x-2005\right).\left(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\right)=0\)

Vì \(\frac{1}{2004}< \frac{1}{2002}\)\(\frac{1}{2003}< \frac{1}{2001}\)

=> \(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\ne0\)

=> \(x-2005=0\)

=> \(x=2005\)

Vậy \(x=2005\)

7 tháng 2 2018

Ta có: \(\frac{x-1}{2004}+\frac{x-2}{2003}=\frac{x-3}{2002}+\frac{x-4}{2001}\)

\(\Leftrightarrow\frac{x-1}{2004}-1+\frac{x-2}{2003}-1=\frac{x-3}{2002}-1+\frac{x-4}{2001}-1\)

\(\Leftrightarrow\frac{x-1-2004}{2004}+\frac{x-2-2003}{2003}=\frac{x-3-2002}{2002}+\frac{x-4-2001}{2001}\)

\(\Leftrightarrow\frac{x-2005}{2004}+\frac{x-2005}{2003}-\frac{x-2005}{2002}-\frac{x-2005}{2001}=0\)

\(\Leftrightarrow\left(x-2005\right)\left(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\right)=0\)

Vì \(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\ne0\)

=> x - 2005 = 0

=> x             = 2005

Vậy x = 2005

=> (x - 1)/2004 - 1 + (x - 2)/2003 - 1 = (x - 3)/2002 -1 + (x - 4)/2001 - 1

=> (x - 2005)/2004 + (x - 2005)/2003 = (x - 2005)/2002 + (x - 2005)/2001

=> (x - 2005)/2004 + (x - 2005)/2003 - (x - 2005)/2002 - (x - 2005)/2001 = 0

=> (x - 2005) * ( 1/2004 + 1/2003 - 1/2002 - 1/2001) = 0

Ta thấy  ( 1/2004 + 1/2003 - 1/2002 - 1/2001) khác 0

=> x - 2005 = 0

=> x = 2005

     

1 tháng 2 2018

\(\frac{x-1}{2004}+\frac{x-2}{2003}-\frac{x-3}{2002}=\frac{x-4}{2001}\)

\(\Leftrightarrow\)\(\frac{x-1}{2004}+\frac{x-2}{2003}=\frac{x-4}{2001}+\frac{x-3}{2002}\)

\(\Leftrightarrow\)\(\frac{x-1}{2004}-1+\frac{x-2}{2003}-1=\)\(\frac{x-4}{2001}-1+\frac{x-3}{2002}-1\)

\(\Leftrightarrow\)\(\frac{x-2005}{2004}+\frac{x-2005}{2003}\)\(=\frac{x-2015}{2001}+\frac{x-2005}{2002}\)

\(\Leftrightarrow\)\(\frac{x-2005}{2004}+\frac{x-2005}{2003}-\frac{x-2005}{2001}-\frac{x-2005}{2002}=0\)

\(\Leftrightarrow\)( x - 2005 ) ( \(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2001}-\frac{1}{2002}\))  =  0

Do  \(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2001}-\frac{1}{2002}\)\(\ne\)0

\(\Rightarrow\)x  -   2005   =  0

\(\Leftrightarrow\)x  =  2005

Vậy  x  =  2005

19 tháng 11 2019

\(\frac{x+1}{2004}+\frac{x+2}{2003}=\frac{x+3}{2002}+\frac{x+4}{2001}\)

\(\Leftrightarrow\frac{x+1}{2004}+1+\frac{x+2}{2003}+1=\frac{x+3}{2002}+1+\frac{x+4}{2001}+1\)

\(\Leftrightarrow\frac{x+2005}{2004}+\frac{x+2005}{2003}=\frac{x+2005}{2002}+\frac{x+2005}{2001}\)

\(\Leftrightarrow\left(x+2005\right)\left(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\right)=0\)

De thay \(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}< 0\Rightarrow x+2005=0\)

\(\Rightarrow x=-2005\)

19 tháng 11 2019

                              Bài giải

\(\frac{x+1}{2004}+\frac{x+2}{2003}=\frac{x+3}{2002}+\frac{x+4}{2001}\)

\(\frac{x+1}{2004}+1+\frac{x+2}{2003}+1=\frac{x+3}{2002}+1+\frac{x+4}{2001}+1\)

\(\frac{x+2005}{2004}+\frac{x+2005}{2003}=\frac{x+2005}{2002}+\frac{x+2005}{2001}\)

\(\frac{x+2005}{2004}+\frac{x+2005}{2003}-\frac{x+2005}{2002}-\frac{x+2005}{2001}=0\)

\(\left(x+2005\right)\left(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\right)=0\)

Do : \(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\ne0\) 

\(\Rightarrow\text{ }x+2005=0\)

\(x=0-2005\)

\(x=-2005\)

7 tháng 11 2015

Mk mới học lớp 6 nên bó tay

11 tháng 3 2016

đáp án x =2015

20 tháng 8 2017

\(\frac{x-1}{2004}+\frac{x-2}{2003}-\frac{x-3}{2002}=\frac{x-4}{2001}\)

=>\(\frac{x-1}{2004}-1+\frac{x-2}{2003}-1-\frac{x-3}{2002}-1=\frac{x-4}{2001}-1\)

=> \(\frac{x-1-2004}{2004}+\frac{x-2-2003}{2003}-\frac{x-3-2002}{2002}=\frac{x-4-2001}{2001}\)

=> \(\frac{x-2005}{2004}+\frac{x-2005}{2003}-\frac{x-2005}{2002}=\frac{x-2005}{2001}\)

=> \(\frac{x-2005}{2004}+\frac{x-2005}{2003}-\frac{x-2005}{2002}-\frac{x-2005}{2001}=0\)

=> \(\left(x-2005\right)\left(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\right)=0\)

Do \(\frac{1}{2004}+\frac{1}{2003}-\frac{1}{2002}-\frac{1}{2001}\ne0\)

=> x - 2005 = 0 => x = 2005

2 tháng 10 2017

\(a.\left(\frac{x+1}{2000}+1\right)+\left(\frac{x+2}{1999}+1\right)+\left(\frac{x+3}{1998}+1\right)+\left(\frac{x+4}{1997}+1\right)=0\)

\(=\frac{x+2001}{2000}+\frac{x+2001}{1999}+\frac{x+2001}{1998}+\frac{x+2001}{1997}=0\)

\(=\left(x+2001\right).\left(\frac{1}{2000}+\frac{1}{1999}+\frac{1}{1998}+\frac{1}{1997}\right)=0\)

\(=>x+2001=0\)

\(x=-2001\)

\(b.\left(\frac{x+1}{1999}-1\right)+\left(\frac{x+2}{2000}-1\right)+\left(\frac{x+3}{2001}-1\right)=\left(\frac{x+4}{2002}-1\right)+\left(\frac{x+5}{2003}-1\right)\)\(+\left(\frac{x+6}{2004}-1\right)\)

\(\frac{x+1998}{1999}+\frac{x+1998}{2000}+\frac{x+1998}{2001}=\frac{x+1998}{2002}+\frac{x+1998}{2003}+\frac{x+1998}{2004}\)

\(\frac{x+1998}{1999}+\frac{x+1998}{2000}+\frac{x+1998}{2001}-\frac{x+1998}{2002}-\frac{x+1998}{2003}-\frac{x+1998}{2004}=0\)

\(\left(x+1998\right).\left(\frac{1}{1999}+\frac{1}{2000}+\frac{1}{2001}-\frac{1}{2002}-\frac{1}{2003}-\frac{1}{2004}\right)=0\)

\(=>x+1998=0\)

\(x=-1998\)

6 tháng 4 2018

dễ quá!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!