a) 2010/1+2009/2+2008/3+ ... +1/2010+2010 : 1+1/2+1/3+ ... +1/2010=
b) 1/2011+1/2010+1/2009+ ... +1/3+1/2 : 2010/1+2009/2+2008/3+ ... +1/2010=
Tính S=2^2010-2^2009-2^2008-...-2-1
S=22010-22009-22008-...-2-1
=> 2S=2. 22010 -2. 22009-2. 22008-....-2.2-2.1
2S=22011-22010-22009-....-22-2
- S=22010-22009-22008-...-2-1
=>S=22011-1
tinh tong
a)s=1+(-2)+3+(-4)+.......+2009+(-2010)
b)s=1+(-2)+(-3)+4+5+6(-6)+(-7)+......+2008+2009+(-2010)
Thực hiện phép tính
S=\(2^{2010}-2^{2009}-2^{2008}...-2-1\)
\(S=-\left(1+2+...+2^{2009}+2^{2010}\right)\)
\(-2S=2\left(1+2+...+2^{2009}+2^{2010}\right)\)
\(\Rightarrow-2S+S=-S=2+2^2+...+2^{2010}+2^{2011}-1-2-...-2^{2009}-2^{2010}\)
\(-S=2^{2011}-1\Rightarrow S=1-2^{2011}\)
S=22010 - 22009 - 22008 -...-2-1
=>2S=2 x 22010 - 2 x 22009 - 2 x 22008 -...-2 x 2 -2 x 1
2S=22011 - 22010 - 22009 - ... - 22 -2
=>S=1-22011
tính 2010*2010-2009*2009+2008*2008-........+2*2-1*1
Bài 2 : So sánh
\(A=\dfrac{2008}{2009}+\dfrac{2009}{2010}+\dfrac{2010}{2011}vàB=\dfrac{2008+2009+2010}{2009+2010+2011}\)
\(B=\dfrac{2008+2009+2010}{2009+2010+2011}=\dfrac{2008}{2009+2010+2011}+\dfrac{2009}{2009+2010+2011}+\dfrac{2010}{2009+2010+2011}\)Ta có : \(\dfrac{2008}{2009}>\dfrac{2008}{2009+2010+2011}\)
\(\dfrac{2009}{2010}>\dfrac{2009}{2009+2010+2011}\)
\(\dfrac{2010}{2011}>\dfrac{2010}{2009+2010+2011}\)\(=>\dfrac{2008}{2009}+\dfrac{2009}{2010}+\dfrac{2010}{2011}>\dfrac{2008+2009+2010}{2009+2010+2011}\)
Hay A > B
Tính S=2^2010-2^2009-2^2008-...-2-1
\(S=2^{2010}-2^{2009}-...-2-1\)
\(2S=2^{2011}-2^{2010}-2^{2009}-....-2^2-2\)
Trừ dưới cho trên:
\(S=2^{2011}-2.2^{2010}+1=2^{2011}-2^{2011}+1=1\)
2010×2010 - 2009×2009 +2008×2008-...+2×2-1×1 ai làm nhanh nhất mk tk cho
\(2010^2-2009^2+2008^2-...+2^2-1^2\)
\(=-\left(1^2-2^2+3^2-...+2009^2-2010^2\right)\)
\(=-\left[1^2+2^2+...+2009^2+2010^2-\left(2^2+4^2+...+2010^2\right)\right]\)
\(=-\left[\frac{2010.\left(2010-1\right)\left(2.2010-1\right)}{6}-2^2\left(1^2+2^2+...+1005^2\right)\right]\)
\(=-\left[2704847285-2^2.\frac{1005\left(1005-1\right)\left(2.1005-1\right)}{6}\right]\)
\(=-\left(2704847285-1351414120\right)=1353433165\)
2010×2010 - 2009×2009 +2008×2008-...+2×2-1×1
=2 x 2010 - 2 x 2009 + .......+ 2 x 2 - 2 x 1
=2x(2010-2009+2008-.......+2-1)
=2x[(2010-2019)+......+(2-1)]
=2x ( 1+ 1+....+1)
=2x1005
=2010
S= 2mu 2010 - 2 mu 2009 - 2 mu 2008 - ...- 2 - 1