A = (1 + 5 + 9 + …+ 1005) + (2 + 6 + 10 + … + 1006) – (3 + 7 + … + 1003) – (4 + 8 + … + 1004)
= 1006 x 252 : 2 + 1008 x 252 : 2 – 1006 x 251 : 2 – 1008 x 251 : 2
= 1006 : 2 + 1008 : 2 = (1008 + 1006) : 2 = 1007
a) Tính Nhanh: 1+2-3-4+5+6-7-8+9+.............+1003+1004-1005-1006+1007.
b)Tính Tổng: 1 - 2 - 3 + 4 + 5 - 6 - 7 + 8+ 9 -......... + 2013 - 2014 -2015 + 2016 + 2017.
giải gấp cho mik nha. Mik tích cho
CMR: 1/1005+1/1006+1/1007+...+1/2009+ 1-1/2+1/3-1/4+...+1/2008+1/2009
chứng minh rằng 3/12.22 + 5/22.32 + 7/32.42 + ...+ 2013/10062.10072 <1
Tính \(\frac{A}{B}\) biết :
A = \(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2007}-\frac{1}{2008}\)
B = \(\frac{1}{1005}+\frac{1}{1006}+\frac{1}{1007}+...+\frac{1}{2007}+\frac{1}{2008}\)
Giúp mình nhé
Bài 1 Tính\(\frac{A}{B}\)biết
a)A=\(\frac{1}{1.300}+\frac{1}{2.301}+\frac{1}{3.302}+...+\frac{1}{101.400}\)
B=\(\frac{1}{1.102}+\frac{1}{2.103}+\frac{1}{3.104}+...+\frac{1}{299.400}\)
b)A=1/2+1/3+1/4+...+1/200
B=1/199+2/198+3/197+...+199/1
c)A=1-1/2+1/3-1/4+...+1/2007-1/2008
B=1/1005+1/1006+1/1007+...+1/2007+1/2008
Chứng tỏ : \(\frac{1005}{1006}+\frac{1006}{1007}+\frac{1007}{1008}+\frac{1008}{1005}\) >4
\(\frac{1005}{1006}+\frac{1006}{1007}+\frac{1007}{1008}+\frac{1008}{1005}>4\)
1 Tính nhanh
2015 - ( 403.5 - 2016) - 2016 + 2^2017 : 2^2015 - 2^2015:4^1007-1-3+4-5-6+11
tính :1+2+2^2+2^3+...+2^1007
