Tính nhanh:
\(\frac{2010.2009-1}{2008.2010+2009}:\frac{1}{1999}\)
2010.2009-1/2008.2010+2009 :1/1999
2010.2009—1/2008.2010+2009:1/1999
đề như thế này hả bạn
\(2010.2009-\frac{1}{2008.2010}+\frac{2009}{\frac{1}{1999}}\)
2010.2009-1/2008.2010+2009:1/1999
\(2010\cdot2009-\frac{1}{2008}\cdot2010+2009:\frac{1}{1999}\)
=\(4038090\)\(-\)\(\frac{1005}{1004}\)\(+4015991\)
\(=8054079,999\)
\(y=\frac{2010.2009-2}{2008+2008.2010}+\frac{-2009.20102010}{20092009.2010}\)
Tính nhanh :
2010.2009-1 / 2008 - 2010 + 2009
2010.2009-1 / 2008 - 2010 + 2009
2010 - 2010 + 2009 - 2009 . 1/2008
= 0+0. 1/2008
= 0
k mk na <3
tính qía trị của biểu thức \(A=-\frac{1}{2010}-\frac{1}{2010.2009}-\frac{1}{2009.2008}-.......-\frac{1}{3.2}-\frac{1}{2.1}\)
-2010.2009+109/2008.2010+1990
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 \(A=\frac{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2010}}{2010\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2010}\right)}=\frac{1}{2010}\)
tính nhanh : \(\frac{2007}{2008}\times\frac{1}{2009}+\frac{2007}{2008}:\frac{2009}{2008}+\frac{1}{2008}\)
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