H24
Những câu hỏi liên quan
Tính nhanh:
a,1/2009+2/2009+3/2009+......2008/2009
b,2010*2010*20092009-2009*2009*20102010/2009*20052005
a, \(\frac{1}{2009}+\frac{2}{2009}+...+\frac{2008}{2009}\\ \frac{\left(1+2008\right)\cdot2008\div2}{2009}=\frac{2017036}{2009}\)
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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 nhanh.(1-1/2)*(1-2/3)*(1-3/4)*...(1-2007/2008)*(1-2009/2010) dấu * là dấu nhân
tính a/b biết:a=1/2+1/3+....+1/2010 ;B=2009/1+2008/2+....+2/2008+1/2009
nhanh mk tk cho
cảm ơn nhìu nhuiuf
Tính nhanh
1* 2010+2*2009+3*2008+....+2010*1 phần [1+2+3+...+2010]+[1+2+3+...+2009]+...+[1+2] +1
dấu * này là nhân
lầm hộ mình nhé
Cho A = 1/2001+2/2009+3/2008+........2009/+ 2010/1, B = 1+1/2+1/3+1/4+1/5+1/6+.......1/2010+1/2011. Tính A/B
Tính tổng:
a,S1=1+(-2)+3+(-4)+..........+2009+(-2010)
b,S2=1+(-2)+(-3)+4+5+(-6)+(-7)+............+2008+2009+(-2010)
a,S1=1+(-2)+3+(-4)+..........+2009+(-2010)
S1=-1.(2010:2)
S1=-1005
b,S2=1+(-2)+(-3)+4+5+(-6)+(-7)+............+2008+2009+(-2010)
S2=-1.(2010:2)
S2=-1.1005
S2=-1005
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Tính tổng sau
A=1-2+3-4+5-....-2008+2009
B=1+2-3-4+5+6-7-...-2007-2008+2009+2010
Bài làm:
\(A=1-2+3-4+5-...-2008+2009\)
\(A=\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+...+\left(2007-2008\right)+2009\)
\(A=-1-1-1-...-1+2009\)(1004 số -1)
\(A=-1004+2009=1005\)
\(B=1+2-3-4+5+6-7-...-2007-2008+2009+2010\)
\(B=1+\left(2-3-4+5\right)+\left(6-7-8+9\right)+...+\left(2006-2007-2008+2009\right)+2010\)
\(B=1+0+0+...+0+2010\)
\(B=2011\)
Học tốt!!!!
Tính nhanh
\(A=\frac{\frac{1}{2}+\frac{1}{3}+....+\frac{1}{2010}}{\frac{2009}{1}+\frac{2008}{2}+...+\frac{1}{2009}}\)
Gọi \(S=\frac{2009}{1}+\frac{2008}{2}+...+\frac{1}{2009}\)
\(\Rightarrow S=\frac{2010-1}{1}+\frac{2010-2}{2}+...+\frac{2010-2009}{2009}\)
\(\Rightarrow S=2010-1+\frac{2010}{2}-1+...+\frac{2010}{2009}-1\)
\(\Rightarrow S=2010+\frac{2010}{2}+...+\frac{2010}{2009}-\left(1+1+..+1\right)\)
\(\Rightarrow S=2010+\frac{2010}{2}+...+\frac{2010}{2009}-2009\)
\(\Rightarrow S=\frac{2010}{2}+\frac{2010}{3}+...+\frac{2010}{2009}+1\)
\(\Rightarrow S=\frac{2010}{2}+\frac{2010}{3}+..+\frac{2010}{2009}+\frac{2010}{2010}\)
\(\Rightarrow S=2010\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2010}\right)\)
Khi đó \(A=\frac{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2010}}{2010\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2010}\right)}=\frac{1}{2010}\)
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