Tính nhanh:
a,1/2009+2/2009+3/2009+......2008/2009
b,2010*2010*20092009-2009*2009*20102010/2009*20052005
tính tổng sau : 2010 x 2010 x 20092009 -2009 x 2009 x 2009 x 20102010/2009 x 20052005
A= 2009 nhân 2010 - 2 / 2008 +2008 nhân 2010
B= 2009 nhân 20102010/ 20092009 nhân 2010
so sánh
2010 nhân 20092009-20102010 nhân 2009
2010 nhân 20092009-20102010 nhân 2009 bằng 0
nhớ k mình nha
Giá trị biểu thức A = 2010 . 20092009 – 2009. 20102010 bằng:
\(A=2010.20092009-2009.20102010\)
\(A=2010.2009.10001-2009.2010.10001\)
\(A=0\)
\(A=2010\cdot20092009-2009\cdot20102010\)
\(A=2010\cdot2009\cdot10001-2009\cdot20102010\)
\(A=20102010\cdot2009-2009\cdot20102010\)
\(A=0\)
Giá trị biểu thức A=2010.20092009-2009.201012010=2009000
tính 2010*2010-2009*2009+2008*2008-........+2*2-1*1
\(B=\frac{2009-\frac{2009}{2001}-\frac{2009}{2002}-\frac{2009}{2003}-\frac{2009}{2004}}{2010-\frac{2010}{2001}-\frac{2010}{2002}-\frac{2010}{2003}-\frac{2010}{2004}}:\frac{2009-\frac{2009}{2005}-\frac{2009}{2006}-\frac{2009}{2007}-\frac{2009}{2008}}{2010-\frac{2010}{2005}-\frac{2010}{2006}-\frac{2010}{2007}-\frac{2010}{2008}}\)
minh lam duoc roi . cach viet phan so ban bam vao o mau vang o cuoi trang .cu di con chuot xuong cuoi trang thi thay 1 o vang , vao xem huong dan la biet ngay ma.
So sánh hai số hữu tỉ 2009/2010 và 20092009/20102010
Có \(\frac{20092009}{20102010}=\frac{2009.10001}{2010.10001}=\frac{2009}{2010}\)
=> \(\frac{2009}{2010}=\frac{20092009}{20102010}\)
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=
so sanh
A=2008/2009+2009/2010+2010+2011
B=2008+2009+2010/2009+2010+2011
Dễ thấy:
\(\frac{2008}{2009}>\frac{2008}{2009+2010+2011}\)
\(\frac{2009}{2010}>\frac{2009}{2009+2010+2011}\)
\(\frac{2010}{2011}>\frac{2010}{2009+2010+2011}\)
=>\(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}>\frac{2008}{2009+2010+2011}+\frac{2009}{2009+2010+2011}+\frac{2010}{2009+2010+2011}\)
Hay \(\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}>\frac{2008+2009+2010}{2009+2010+2011}\)
Vậy A > B