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Ta có: x=2011 \(\Rightarrow\)x+1=2012
\(\Rightarrow A=x^{2011}-\left(x+1\right).x^{2010}\)\(+\left(x+1\right)x^{2009}\)\(-\left(x+1\right)x^{2008}+...\)\(-\left(x+1\right)x^2+\left(x+1\right)x-1\)
=\(x^{2011}\)\(-x^{2011}-x^{2010}+x^{2010}+x^{2009}-x^{2009}-\)...\(-x^2+x^2+x-1\)
= \(x-1=2011-1=2010\)
=
+) Xét \(x\ge2010\) có:
\(2012=x-2010+x-2008\)
\(\Rightarrow2x-4018=2012\)
\(\Rightarrow2x=6030\)
\(\Rightarrow x=3015\) ( t/m )
+) Xét \(2008\le x< 2010\) ta có:
\(2012=2010-x+x-2008\)
\(\Rightarrow2=2012\) ( loại )
+) Xét \(x< 2008\) có:
\(2012=2010-x+2008-x\)
\(\Rightarrow2012=4018-2x\)
\(\Rightarrow2x=2006\)
\(\Rightarrow x=1003\left(tm\right)\)
Vậy x= 3015 hoặc x = 1003
Lập bảng xét dấu:
x 2008 2010
x - 2008 - 0 + || +
x-2010 - || - 0 +
TH1:x < 2008 . PT có dạng:\(2018-x+2010-x=2012\)
\(\Rightarrow4028-2x=2012\)
\(\Rightarrow2x=2016\)
\(\Rightarrow x=1008\left(TM\right)\)
TH2:\(2008\le x< 2010\).PT có dạng:\(x-2008+2010-x=2012\)
\(\Rightarrow0x+2=2012\)
\(\Rightarrow0x=2010\left(koTM\right)\)
TH3:x > 2010.PT có dạng:\(x-2010+x-2008=2012\)
\(\Rightarrow2x-4018=2012\)
\(\Rightarrow2x=6030\)
\(\Rightarrow x=3015\left(TM\right)\):
Vậy nghiệm PT là 3015 và 1008
tách /x-2010/và/x-2008/ ra, ta đc:
/x-2010/=2012, làm 2 trường hợp:
TH1:x-2010=2012 =>x=4022
TH2:x-2010=-2012 =>x=-2
vậy x=4022 và -2
/x-2008/=2012, làm 2 trường hợp:
TH1:x-2008=2012 =>x=4020
TH2:x-2008=-2012=>x=-4
vậy x=4020 và -4
kết mk nha!
=20122011-2012.20122010+2012.20122009-.......................-2012.20122-1
còn lại tự làm nhá
\(\dfrac{x+4}{2010}+\dfrac{x+3}{2011}=\dfrac{x+2}{2012}+\dfrac{x+1}{2013}\)
\(=>\dfrac{x+4}{2010}+1\))+(\(\dfrac{x+3}{2011}+1\))=\(\left(\dfrac{x+2}{2012}+1\right)\)+\(\left(\dfrac{x+1}{2013}+1\right)\)
=>\(\dfrac{x+2014}{2010}+\dfrac{x+2014}{2011}=\dfrac{x+2014}{2012}+\dfrac{x+2014}{2013}\)
=>x+2014(\(\dfrac{1}{2010}+\dfrac{1}{2011}-\dfrac{1}{2012}-\dfrac{1}{2013}\))=0
ta thấy \(\dfrac{1}{2010}>\dfrac{1}{2011}>\dfrac{1}{2012}>\dfrac{1}{2013}\)
=>\(\dfrac{1}{2010}+\dfrac{1}{2011}-\dfrac{1}{2012}-\dfrac{1}{2013}>0\)
để A=0
\(\Leftrightarrow x+2014=0\)
\(\Leftrightarrow\)x=-2014
a)\(\dfrac{x+4}{2010}+\dfrac{x+3}{2011}=\dfrac{x+2}{2012}+\dfrac{x+1}{2013}\)
\(\Rightarrow\left(\dfrac{x+4}{2010}+1\right)+\left(\dfrac{x+3}{2011}+1\right)=\left(\dfrac{x+2}{2012}+1\right)+\left(\dfrac{x+1}{2013}+1\right)\)\(\Rightarrow\dfrac{x+2014}{2010}+\dfrac{x+2014}{2011}=\dfrac{x+2014}{2012}+\dfrac{x+2014}{2013}\)\(\Rightarrow\dfrac{x+2014}{2010}+\dfrac{x+2014}{2011}-\dfrac{x+2014}{2012}-\dfrac{x+2014}{2013}=0\)
\(\Rightarrow\left(x+2014\right)\left(\dfrac{1}{2010}+\dfrac{1}{2011}-\dfrac{1}{2012}-\dfrac{1}{2013}\right)=0\)Mà \(\dfrac{1}{2010}+\dfrac{1}{2011}-\dfrac{1}{2012}-\dfrac{1}{2013}\ne0\)
\(\Rightarrow x+2014=0\)
\(\Rightarrow x=-2014\)