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\(S=2^{2010}-2^{2009}-2^{2008}-...-2-1\)
\(S=2^{2010}-\left(2^{2009}+2^{2008}+...+2+1\right)\)
Đặt \(A=1+2+...+2^{2008}+2^{2009}\)
\(\Rightarrow2A=2+2^2+..+2^{2010}\)
\(\Rightarrow A=2^{2010}-1\)
\(\Rightarrow S=2^{2010}-\left(2^{2010}-1\right)\)
\(\Rightarrow S=1\)
S = 22010 - 22009 - 22008 - ... - 2 - 1
S= 22010 - ( 22009 + 22008 + ... + 2 + 1 )
Đặt A = 22009 + 22008 + .... + 2 + 1
2A = 2 . ( 22009 + 22008 + .... + 2 + 1
2A = 22010 + 22009 + .... + 22 + 2
2A - A = 22010 + 22009 + ...... + 22 + 2 - 22009 - 22008 - .... - 2 - 1
A = 22010 - 1
Thay A vào S ta có :
S = 22010 - ( 22010 - 1 )
S = 22010 - 22010 + 1
S = 0 + 1
S = 1
Vậy S = 1
=> S = 22010 - ( 22009 + 22008 + .... + 2 + 1 )
Đặt A = 1 + 2 + ... + 22008 + 22009
=> 2A = 2 ( 1 + 2 + ... + 22008 + 22009 )
= 2 + 22 + ... + 22009 + 22010
2A - A = ( 2 + 22 + ... + 22009 + 22010 ) - ( 1 + 2 + ... + 22008 + 22009 )
A = 22010 - 1
=> S = 22010 - ( 22010 - 1 ) = 22010 - 22010 + 1 = 0 + 1 = 1
a) \(S=1+2+2^2+...+2^{100}\)
\(2S=2+2^2+2^3+...+2^{101}\)
\(2S-S=\left(2+2^2+...+2^{101}\right)-\left(1+2+...+2^{100}\right)\)
\(S=2^{101}-1\)
b) \(X=2^{2012}-2^{2011}-...-2-1\)
\(X=2^{2012}-\left(1+2+...+2^{2011}\right)\)
Đặt \(X=2^{2012}-Y\)
Ta có :
\(Y=1+2+...+2^{2011}\)
\(2Y=2+2^2+...+2^{2012}\)
\(2Y-Y=\left(2+2^2+...+2^{2012}\right)-\left(1+2+...+2^{2011}\right)\)
\(Y=2^{2012}-1\)
\(\Rightarrow X=2^{2012}-2^{2012}+1\)
\(\Rightarrow X=1\)
\(\Rightarrow2010X=2010\)
a/ 2H=2^2011-2^2010-2^2009-...-2
=> 2H-H=2^2011-2^2010-2^2009-...-2-(2^2010-2^2009-2^2008-...-1)
H=2^2011-2^2010-2^2009-...-2-2^2010+2^2009+2^2008+...+1
H=2^2011-2^2010-2^2010-1
H=2^2011-2.2^2010-1
H=2^2011-2^2011-1
H=-1 => 2010^-1=1/2010
b/ M=1 + 1/2(1+2) + 1/3(1+2+3) + 1/4(1+2+3+4) + ... + 1/16(1+2+3+...+16)
M= 1+1/2.(2.3/2) + 1/3.(3.4/2) + 1/4.(4.5/2) + ... + 1/16.(16.17/2)
M= 1 + 3/2 +4/2 + 5/2 + ... + 17/2
Cùng mẫu số rồi Tự tính nhé
có 1 công thức làm bài này nè em : 1+2=3=2.3/2, 1+2+3=6=3.4/2, 1+2+3+4=10=4.5/2 ....
\(S=2^{2010}-2^{2009}-2^{2008}-...-2-1\)
\(\Rightarrow2S=2.\left(2^{2010}-2^{2009}-2^{2008}-...-2-1\right)\)
\(\Rightarrow2S=2^{2011}-2^{2010}-2^{2009}-...-2^2-2\)
Có \(2S-S=\left(2^{2011}-2^{2010}-2^{2009}-...-2^2-2\right)-\left(2^{2010}-2^{2009}-2^{2008}-...-2-1\right)\)
\(S=2^{2011}-2^{2010}-2^{2009}-...-2^2-2-2^{2010}+2^{2009}+2^{2008}+...+2+1\)
\(S=2^{2011}+1\)
\(S=-\left(1+2+...+2^{2009}+2^{2010}\right)\)
\(-2S=2\left(1+2+...+2^{2009}+2^{2010}\right)\)
\(\Rightarrow-2S+S=-S=2+2^2+...+2^{2010}+2^{2011}-1-2-...-2^{2009}-2^{2010}\)
\(-S=2^{2011}-1\Rightarrow S=1-2^{2011}\)
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