(5 * 2010 / 1) * (5 * 2010 / 2) * .......*(5 * 2010 / 2009)
|3x-5|=2009(2010^2009+2010^2008+....+2010+1)-2010^2010=5
\(\left|3x-5\right|=2009\left(2010^{2009}+2010^{2008}+...+2010+1\right)-2010^{2010}+5\)
\(_{\left|3x-5\right|=2009\left(2010^{2009}+2010^{2008}+...+2010+1\right)-2010^{2010}+5}\)
so sánh A=1+9+9^2+...+9^2010/1+9+9^2+...+9^2009 và B=1+5+5^2+...+5^2010/1+5+5^2+...+5^2009
So sánh: (19^2009+5^2009)^2010 và (19^2010+5^2010)^2009
so sanh
(19^2009+5^2009)^2010 va (19^2010+5^2010)^2009
BT1: Tính
5) \(\dfrac{1}{1+\dfrac{2009}{2011}+\dfrac{2009}{2010}}+\dfrac{1}{1+\dfrac{2010}{2009}+\dfrac{2010}{2011}}+\dfrac{1}{1+\dfrac{2011}{2009}+\dfrac{2011}{2010}}\)
=\(\dfrac{1}{2009.\left(\dfrac{1}{2009}+\dfrac{1}{2011}+\dfrac{1}{2010}\right)}+\dfrac{1}{2010.\left(\dfrac{1}{2010}+\dfrac{1}{2009}+\dfrac{1}{2011}\right)}+\dfrac{1}{2011.\left(\dfrac{1}{2011}+\dfrac{1}{2009}+\dfrac{1}{2010}\right)}\)\(=\dfrac{1}{2009}:\left(\dfrac{1}{2009}+\dfrac{1}{2010}+\dfrac{1}{2011}\right)+\dfrac{1}{2010}:\left(\dfrac{1}{2009}+\dfrac{1}{2010}+\dfrac{1}{2011}\right)+\dfrac{1}{2011}:\left(\dfrac{1}{2009}+\dfrac{1}{2010}+\dfrac{1}{2011}\right)\)
\(=\left(\dfrac{1}{2009}+\dfrac{1}{2010}+\dfrac{1}{2011}\right):\left(\dfrac{1}{2009}+\dfrac{1}{2010}+\dfrac{1}{2011}\right)=1\)
\(A=\dfrac{5^{2011}-5^{2010}+5^{2009}-5^{2008}+....+5-1}{5^{2013}-5^{2012}+5^{2011}-5^{2010}+....+5-1}\) \(B=\dfrac{5^{2009}-5^{2008}+5^{2007}-5^{2006}+....+5-1}{5^{2011}-5^{2010}+5^{2009}-5^{2008}+....+5-1}\)
So sánh A và B
C/m 3/1*1+2*2+5/2*2+3*3+...+4019/2009*2009+2010*2010<1