Tính A= 2009/2+2008/(2^2)+2007/(2^3)+...+3/(2^2007)+2/(2^2008)+1/(2^2009)
Tính tỉ số B A , biết: 2008 1 2007 2 ... 3 2006 2 2007 1 2008 2009 1 2008 1 2007 1 ... 4 1 3 1 2 1 = + + + + + = + + + + + + B A
A=(2008/1+2007/2+...........+2/2007+2/2008)/(1/2+1/3+........+1/2008+1/2009)
so sánh 2008 với tổng 2009 số hạng sau\(s=\frac{2008+2007}{2009+2008}+\frac{^{2008^2+2007^2}}{2009^2+2008^2}+.....+\frac{2008^{2009}+2007^{2009}}{2009^{2009}+2008^{2009}}\)
Tính nhanh :a)2/5+4/5 nhân 5/2
b)2008/2009-2009/2008+1/2009+2007/2008
tính tổng sau :\(c=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{\frac{5}{2008}-\frac{5}{2009}-\frac{5}{2010}}+\)\(\frac{\frac{2}{2007}-\frac{2}{2008}-\frac{2}{2009}}{\frac{3}{2007}-\frac{3}{2008}-\frac{3}{2009}}\)
\(C=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{\frac{5}{2008}-\frac{5}{2009}-\frac{5}{2010}}+\frac{\frac{2}{2007}-\frac{2}{2008}-\frac{2}{2009}}{\frac{3}{2007}-\frac{3}{2008}-\frac{3}{2009}}\)
\(=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{5.\left(\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}\right)}+\frac{2.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}{3.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}\)
\(=\frac{1}{5}+\frac{2}{3}\)
\(=\frac{13}{15}\)
Tính tỉ số A/B biết:
A=1/2+1/3+1/4+...+1/2007+1/2008+1/2009
B=2008/1+2007/2+2006/3+...+2/2007+1/2008
*A/B là phân số.
tính ttir số a/b
a=1/2+1/3+1/4+...........+1/2007+1/2008+1/2009
b=2008/1+2007/1+2006/1+......2/2007+1/2008
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Tính A/ B biết
A= 2008+ 2007/2 + 2006/3 + 2005/4+....+ 2/2007+ 1/2008 ; B = 1/2+1/3+1/4+1/5+....1/2008+1/2009
Tính tỉ số a/b, biết :
A=1/2+1/3+1/4+1/5+.....+1/2008+1/2009
B=2008/1+2007/2+2006/3+....+2/2007+1/2008