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có 2014/1+2013/2+2012/3+...+2/2013+1/2014=[1+(2013/2)]+[1+(2012/3)]+...+[1+(2/2013)]+[1+(1/2014)]+1
=2015/2+2015/3+...+2015/2014+2015/2015=2015.[1/2+1/3+..+1/2015)
vậy (1/2+1/3+...+1/2015).x=(1/2+1/3+...+1/2015).2015
x=2015
\(\frac{1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2012}}{\frac{2013}{1}+\frac{2014}{2}+\frac{2015}{3}+...+\frac{4024}{2012}-2012}\)
\(=\frac{1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2012}}{\left(\frac{2013}{1}-1\right)+\left(\frac{2014}{2}-1\right)+\left(\frac{2015}{3}-1\right)+...+\left(\frac{4024}{2012}-1\right)}\)
\(=\frac{1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2012}}{\frac{2012}{1}+\frac{2012}{2}+\frac{2012}{3}+...+\frac{2012}{2012}}\)
\(=\frac{1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2012}}{2012.\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2012}\right)}\)
\(=\frac{1}{2012}\)
Ủng hộ mk nha ^_-
Đặt A = 1 + 2 + 22 + 23+ ...+ 22012
2A = 2 + 22 + 23 + 24 +....+22013
Lấy 2A - A = 2 + 22 +23 + 24 +....+22013 - 1-2-22- 23 - ... - 22012
A = 22013 - 1
Khi đó : M = A / 22014 -2
= 22013 - 1 / 2.( 22013 - 1 )
= 1/2
Vậy M= 1/2
Đặt tử số là A = 1 + 2 + 22 + 23 + ... + 22012
2A = 2 + 22 + 23 + 24 + ... + 22013
2A - A = (2 + 22 + 23 + 24 + ... + 22013) - (1 + 2 + 22 + 23 + ... + 22012)
A = 22013 - 1
=> \(M=\frac{2^{2013}-1}{2^{2014}-2}=\frac{2^{2013}-1}{2.\left(2^{2013}-1\right)}=\frac{1}{2}\)
ĐẶT \(A=1+2+2^2+...+2^{2012}\)
\(\Rightarrow2A=2+2^2+2^3+...+2^{2013}\)
\(\Rightarrow2A-A=2^{2013}-1\Rightarrow A=2^{2013}-1\)
vẬY \(\frac{1+2+2^2+...+2^{2012}}{2^{2014}-2}=\frac{2^{2013}-1}{2\left(2^{2013}-1\right)}=\frac{1}{2}\)
Đặt \(S=1+2+2^2+2^3+...+2^{2012}\)
\(\Leftrightarrow2S=2+2^2+2^3+2^4+...+2^{2013}\)
\(\Leftrightarrow2S-S=2+2^2+2^3+2^4+...+2^{2013}-1-2-2^2-2^3-2^{2012}\)
\(\Leftrightarrow S=2^{2013}-1\)
Thay \(S=2^{2013}-1\) vào phân thức \(\frac{1+2+2^2+2^3+...+2^{2012}}{2^{2014}-2}\), ta được:
\(\frac{1+2+2^2+2^3+...+2^{2012}}{2^{2014}-2}=\frac{2^{2013}-1}{2^{2014}-2}=\frac{2^{2013}-1}{2\left(2^{2013}-1\right)}=\frac{1}{2}\)