tính nhanh : \(\frac{2007}{2008}\times\frac{1}{2009}+\frac{2007}{2008}:\frac{2009}{2008}+\frac{1}{2008}\)
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\(=\left(\frac{2007}{2008}+\frac{1}{2008}\right)+\left(\frac{2007}{2008}.\frac{2008}{2009}+\frac{1}{2009}\right)\)
\(=1+\frac{2008}{2009}=\frac{4017}{2009}\)
\(\frac{2007}{2008}+\frac{1}{2009}+\frac{2007}{2008}:\frac{2009}{2008}+\frac{1}{2008}\)
\(=\frac{2007}{2008}+\frac{1}{2009}+\frac{2007}{2009}+\frac{1}{2008}\)
\(=\left(\frac{2007}{2008}+\frac{1}{2008}\right)+\left(\frac{2007}{2009}+\frac{1}{2009}\right)\)
\(=1+\frac{2008}{2009}\)
\(=\frac{4017}{2009}\)
\(C=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{\frac{5}{2008}-\frac{5}{2009}-\frac{5}{2010}}+\frac{\frac{2}{2007}-\frac{2}{2008}-\frac{2}{2009}}{\frac{3}{2007}-\frac{3}{2008}-\frac{3}{2009}}\)
\(=\frac{\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}}{5.\left(\frac{1}{2008}-\frac{1}{2009}-\frac{1}{2010}\right)}+\frac{2.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}{3.\left(\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}\right)}\)
\(=\frac{1}{5}+\frac{2}{3}\)
\(=\frac{13}{15}\)
=2008/2009-2009/2008+1/2009+2007/2008
=(2008/2009+1/2009)-(2009/2008-2007/2008)
=1-1/1004
=1003/1004
\(\frac{2008}{2009}-\frac{2009}{2008}+\frac{1}{2009}+\frac{2007}{2008}\)
=\(\left(\frac{2008}{2009}+\frac{1}{2009}\right)-\left(\frac{2009}{2008}-\frac{2007}{2008}\right)\)
=\(1-\frac{2}{2008}\)
=\(1-\frac{1}{1004}\)
=\(\frac{1003}{1004}\)
Chúc bn làm tốt nha!!!
có : Q = [ 2 + 2^2 ] + [ 2^3 +2^4] + ... + [2^9 + 2^10]
Q = 2 [1+2] +2^3[1 +2]+ ...+ 2^9 [1+2]
Q = 2 . 3+2^3 .3 +... + 2^9 .3
Q = 3. [ 2 + 2^3 +... + 2^9]
Vậy Q chia hết cho 3
\(\frac{2007}{2008}\)\(+\)\(\frac{2008}{2009}\)\(=\)\(\frac{2007}{2008}\)\(+\)\(\frac{2008}{2009}\)
k mk nha!!! *o~
\(\frac{2007}{2008}+\frac{2008}{2009}=\frac{2007}{2008}+\frac{2008}{2009}\)
nha ^_^
Nguyễn Vân Anh
2007/2008 x 1/2009 + 2007/2008 : 2009/2008 + 1/2008
= 2007/2008 x 1/2009 + 2007/2008 x 2008/2009 + 1/2008
= 2007/2008 x (1/2009 + 2008/2009) + 1/2008
= 2007/2008 x 1 + 1/2008
= 2007/2008 + 1/2008
= 2008/2008 = 1