Tìm x :2011+2010+2009+...+x=2011
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\(\frac{x-2010-2011}{2009}+\frac{x-2009-2011}{2010}+\frac{x-2009-2010}{2011}=3\)
\(\Leftrightarrow\left(\frac{x-2010-2011}{2009}-1\right)+\left(\frac{x-2009-2011}{2010}-1\right)+\left(\frac{x-2009-2010}{2011}-1\right)=0\)
\(\Leftrightarrow\frac{x-6030}{2009}+\frac{x-6030}{2010}+\frac{x-6030}{2011}=0\)
\(\Leftrightarrow\left(x-6030\right)\left(\frac{1}{2009}+\frac{1}{2010}+\frac{1}{2011}\right)\)
\(\Leftrightarrow x-6030=0\)(vì \(\frac{1}{2009}+\frac{1}{2010}+\frac{1}{2011}>0\))
\(\Leftrightarrow x=6030\)
Vậy ................
`(2011xx2020-1)/(2009xx2011+2010)`
`=((2009+1)xx2011-1)/(2009xx2011+2010)`
`=(2009xx2011+2011-1)/(2009xx2011+2010)`
`=(2009xx2011+2010)/(2009xx2011+2010)`
`=1`
\(\dfrac{2011.2010-1}{2009.2011+2010}\)
= \(\dfrac{2011.2009+2011-1}{2009.2011+2010}\)
= \(\dfrac{2011.2009+2010}{2009.2011+2010}\)
= 1
a) \(\frac{x+4}{2009}+1+\frac{x+3}{2010}+1=\frac{x+2}{2011}+1+\frac{x+1}{2012}\)
\(\frac{x+4+2009}{2009}+\frac{x+3+2010}{2010}=\frac{x+2+2011}{2011}+\frac{x+2+2012}{2012}\)
\(\frac{x+2013}{2009}+\frac{x+2013}{2010}-\frac{x+2013}{2011}-\frac{x+2013}{2012}=0\)
\(\left(x+2013\right).\left(\frac{1}{2009}+\frac{1}{2010}-\frac{1}{2011}-\frac{1}{2012}\right)=0\) (1)
Vì \(\left(\frac{1}{2009}+\frac{1}{2010}-\frac{1}{2011}-\frac{1}{2012}\right)\ne0\)
Nên biểu thức (1) xảy ra khi \(x+2013=0\)
\(x=-2013\)
b) \(\left(x-2011\right)\left(\frac{1}{2010}+\frac{1}{2011}+\frac{1}{2012}-\frac{1}{2013}-\frac{1}{2014}\right)=0\) (2)
Vì \(\left(\frac{1}{2010}+\frac{1}{2011}+\frac{1}{2012}-\frac{1}{2013}-\frac{1}{2014}\right)\ne0\)
Nên biểu thức (2) xảy ra khi \(x-2011=0\)
\(x=2011\)
A = 2011 x (2009 + 1) - 1/ 2011 x 2009 + 2010
A = 2011 x 2009 + 2011 x 1 - 1/2011 x 2009 + 2010
A = 2011 x 2009 + 2010/2011 x 2009 + 2010
A = 1
B.
2011 + 2010 + 2009 + ... + x = 2011
2011 +( 2010 + 2009 + ... + x )= 2011
2010 + 2009 + ... + x = 2011 − 2011
2010 + 2009 + ... + x = 0
→ Từ 2010->x có: x số
→ 2 x + 2010 .x = 0
x + 2010 .x = 0.2
x + 2010 .x = 0
⇒x + 2010 = 0
x = 0 - 2010
x = −2010
Vậy x = −2010