Tìm x biết x=(2009:2)+(2008:22)+(2007:23)+...+(1:22009)
Tìm XEZ biết
a)x+(x+1)+(x+2)+........+2008=2008
b)2009+2008+2007+........+(x+1)+x=2009
a)=> (2008+x).2008/2=2008
=>(2008+x)=2
=>x=-2006
Tìm x biết : x - 1 / 2009 + x - 2 / 2008 = x - 3 / 2007 + x- 4 / 2006
\(\frac{x-1}{2009}+\frac{x-2}{2008}=\frac{x-3}{2007}+\frac{x-4}{2006}\)
\(\Leftrightarrow\frac{x-1}{2009}-1+\frac{x-2}{2008}-1=\frac{x-3}{2007}-1+\frac{x-4}{2006}-1\)
\(\Leftrightarrow\frac{x-2010}{2009}+\frac{x-2010}{2008}-\frac{x-2010}{2007}-\frac{x-2010}{2006}=0\)
\(\Leftrightarrow\left(x-2010\right)\left(\frac{1}{2009}+\frac{1}{2008}-\frac{1}{2007}-\frac{1}{2006}\ne0\right)=0\)
\(\Leftrightarrow x=2010\)
Tìm x thuộc Z, biết :
a/ x + (x + 1) + (x + 2)+...+2008 = 2008
b/ 2009 + 2008 + 2007 +...+(x + 1) + x + 2009
Tìm x biết:
(x - 1)/2009 + (x - 2)/2008 = (x - 3)/2007 + (x - 4)/2006
\(\Leftrightarrow\left(\frac{x-1}{2009}-1\right)+\left(\frac{x-2}{2008}-1\right)=\left(\frac{x-3}{2007}-1\right)+\left(\frac{x-4}{2006}-1\right)\)
\(\Leftrightarrow\frac{x-2010}{2009}+\frac{x-2010}{2008}=\frac{x-2010}{2007}+\frac{x-2010}{2006}\)
\(\Leftrightarrow\frac{x-2010}{2009}+\frac{x-2010}{2008}-\frac{x-2010}{2007}-\frac{x-2010}{2006}=0\)
\(\Leftrightarrow\left(x-2010\right)\left(\frac{1}{2009}+\frac{1}{2008}+\frac{1}{2007}+\frac{1}{2006}\right)=0\)
\(\Rightarrow x-2010=0\Rightarrow x=2010\)
Tìm x∈Z biết
\(\dfrac{x+4}{2008}+\dfrac{x+3}{2007}=\dfrac{x+2}{2009}+\dfrac{x+1}{2010}\)
Tìm x,biết
x+4/2007 + x+3/2008 = x+2/2009 + x+1/2010
(x-4)/2007 + (x-3)/2008)= (x-2)/2009 + (x-1)/2010
=[(x-4)/2007 -1]+[(x-3)/2008 -1]=[(x-2)/2009 -1]+[(x-1)/2010 -1]
=(x-2011)/2007+(x-2011)/2008=(x-2011)/...
=(x-2011)(1/2007+1/2008-1/2009-1/2010)...
suy ra x=2010
Tìm x biết :
\(\frac{2-x}{2007}-1=\frac{1-x}{2008}-\frac{x}{2009}\)
\(\dfrac{x}{2008}+\dfrac{x}{2009}-\dfrac{x}{2007}=1+\dfrac{1}{2008}-\dfrac{1}{2009}-\dfrac{2}{2007}\)
\(\Rightarrow x = \dfrac{2007.2008.2009+2009.2007-2008.2007-2.2008.2009}{2009.2007+2008.2007-2008.2009}\)
Tìm x thuộc Z biết :
2009 + 2008 + 2007 +...... ( x + 1) + x = 2009
tìm x,biết:\(\frac{x+1}{2009}+\frac{x+2}{2008}=\frac{x+3}{2007}+\frac{x+4}{2006}\)
\(\Rightarrow\left(\frac{x+1}{2009}+1\right)+\left(\frac{x+2}{2008}+1\right)=\left(\frac{x+3}{2007}+1\right)+\left(\frac{x+4}{2006}+1\right)\)
\(\Rightarrow\left(\frac{x+1}{2009}+\frac{2009}{2009}\right)+\left(\frac{x+2}{2008}+\frac{2008}{2008}\right)=\left(\frac{x+3}{2007}+\frac{2007}{2007}\right)+\left(\frac{x+4}{2006}\frac{2006}{2006}\right)\)
\(\Rightarrow\frac{x+2010}{2009}+\frac{x+2010}{2008}=\frac{x+2010}{2007}+\frac{x+2010}{2006}\)
\(\Rightarrow\frac{x+2010}{2009}+\frac{x+2010}{2008}-\frac{x+2010}{2007}-\frac{x+2010}{2006}=0\)
\(\Rightarrow\left(x+2010\right)\left(\frac{1}{2009}+\frac{1}{2008}-\frac{1}{2007}-\frac{1}{2006}\right)=0\)
Vì \(\frac{1}{2009}+\frac{1}{2008}-\frac{1}{2007}-\frac{1}{2006}\ne0\)
=>x+2010=0
=>x=-2010
Vậy x = -2010