G=1/1-1/2+1/3-1/4+...+1/2005+1/2006 va H=(1/1+1/2+1/3+....+1/2006)-2.(1/2+1/4+.....+1/2006)
Những câu hỏi liên quan
2008+2007/2+2006/3+2005/4+2005/5+........................3/2006+2/2007+1/2008
1/2+1/3+1/4+1/5+....................+1/2009
2008-1/2008=2007/2008
1/2-1/2009=2007/2009
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2008+2007/2+2006/3+2005/4+2005/5+........................3/2006+2/2007+1/2008
1/2+1/3+1/4+1/5+....................+1/2009
Giải phương trình (1/1*2*3+1/2*3*4+1/3*4*5+...+1/2005*2006*2007)x=1*2+2*3+...+2006*2007
Cho A =1/1-1/2+1/3-1/4+...+1/2005+1/2006
B=(1/1+1/2+1/2006)-2x(1/2+1/4+...+1/2006)
a)So sánh A và B
b)Chứng minh rằng A=1/1004+1/1005+...1/2006
a,\(A=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2005}-\frac{1}{2006}\)
\(A=\left(1+\frac{1}{3}+...+\frac{1}{2005}\right)-\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2006}\right)\)
\(A=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2006}\right)-2\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2006}\right)\)
\(=B\left(ĐPCM\right)\)
b, \(A=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2006}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{1003}\right)\)
\(A=\frac{1}{1004}+\frac{1}{1005}+...+\frac{1}{2006}\)
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ui ghi lộn, chữ đpcm chuyển xuống dòng cuối cùng nhé :v
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tính M :N biết: N=1/2+1/3+1/4+......+1/2007+1/2008 và M= 2007/1+2006/2+2005/3+......+2/2006+1/2007
\(\frac{M}{N}=\frac{\frac{1}{2007}+\frac{2}{2006}+......+\frac{2006}{2}+\frac{2007}{1}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+.......+\frac{1}{2006}+\frac{1}{2007}}\)
\(\frac{M}{N}=\frac{\frac{1}{2007}+1+\frac{2}{2006}+1+.......+\frac{2007}{1}+1+\frac{2008}{2008}-2008}{\frac{1}{2008}+\frac{1}{2007}+\frac{1}{2006}+.....+\frac{1}{2}}\)
\(\frac{M}{N}=\frac{\frac{2008}{2007}+\frac{2008}{2006}+....+\frac{2008}{1}+\frac{2008}{2008}-2008}{\frac{1}{2008}+........+\frac{1}{2}}\)
đến đây là ra rùi ha
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ê tớ chẳng hiểu gì cả
cậu làm tắt à
please cậu giúp tớ cả bài đi mà
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Cho: A= 1/2 + 1/3 + 1/4+ ... +1/2008
B= 2007/1 + 2006/2 + 2005/3 +... +2/2006 + 1/2007
Tính B/A
chịuiuiuiuiuiuiuiuiuiuiuiu
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1 Tính
A (1-1/2) * (1-1/3 ) * (1-1/4 ) * .....*(1-1/19)* ( 1-1/20)
B 3/2 * 4/3 * 6/5* ......* 2006/2005 * 2007/2006 * 2008/2007
\(A=\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot......\cdot\left(1-\frac{1}{20}\right)\)
\(A=\frac{1}{2}\cdot\frac{2}{3}\cdot......\cdot\frac{19}{20}\)
\(A=\frac{1.2.3.....19}{2.3........20}\)
\(A=\frac{1}{20}\)
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Cho : A = 1/1*2+1/3*4+1/5*6+.....+1/2003*2004+1/2005*2006
B=1/1004*2006+1/1005*2005+1/1006*2004+....+1/2006*1004
Tinh: A/B
\(\frac{\frac{2006}{2}+\frac{2006}{3}+\frac{2006}{4}+...........+\frac{2006}{2007}}{\frac{2006}{1}+\frac{2005}{2}+\frac{2004}{3}+.............+\frac{1}{2006}}\)
Đặt biểu thức là A ta có:
\(A=\frac{\frac{2006}{2}+\frac{2006}{3}+\frac{2006}{4}+...+\frac{2006}{2007}}{\frac{2006}{1}+\frac{2005}{2}+\frac{2004}{3}+...+\frac{1}{2006}}\)
\(\Rightarrow A=\frac{2006.\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2007}\right)}{1+\left(1+\frac{2005}{2}\right)+\left(1+\frac{2004}{3}\right)+...+\left(1+\frac{1}{2006}\right)}\)
\(\Rightarrow A=\frac{2006.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2007}\right)}{1+\frac{2007}{2}+\frac{2007}{3}+...+\frac{2007}{2006}}\)
\(\Rightarrow A=\frac{2006.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2007}\right)}{2007.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2006}+\frac{1}{2007}\right)}\)
\(\Rightarrow A=\frac{2006}{2007}\)
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