Ta có :a=1/2+1/4+1/6+...+1/1008.Tính A
9.2^x.(2^1005-2^1002+.....+2^3-1)=2^1008-1 *
A=2^1005-2^1002+...+2^3-1 2^3 .
A=2^2.(2^1005-2^1002+......+2^3-1) 8.
A=2^1008-2^1005+.....+2^6-2^3
A=2^1005-2^1002+.....+2^3-1 8.A+A=2^1008-1 9.
A=2^1008-1
Thay 9.a=2^1008-1 vào * ta có: 2^x.(2^1008-1)=2^1008-1
2^x=(2^1008-1):(2^1008-1)
2^x=1
2^x=2^0
x=0
vậy x=0
Lập đề bài cho bài toán này
Cho:
A= 1/1*2+1/3*4+1/5*6+...+1/2013*2014
B=1/1008*2014+1/1009*2013+...+1/2014*1008
Tính A/B
Tính A biết A= 1008^2(1008^3 +1)-1008(1008^4-2)-1008^2
A=1/1*2 + 1/3*4 + 1/5*6 + ... +1/2013*2014
B=1/1008*2014 + 1/1009*2013 + 1/1010*2012+ ... + 1/2014*1008
A=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{2013}-\frac{1}{2014}\)
A=1-1/2-1/3-1/4-...-1/2012. B = 1/1007+1/1008+1/1009+1/2012 tính (A)/(B)^2013
Rút gọn biểu thức A= 1 1/2 x 1 1/3 x 1 1/4 x ... x 1 1/2015 ta được A= ????????????????????
Các bạn cho mình hỏi luôn 1008 có phải là kết quả của bài ko ?????????????????????
So sánh A=1/1008(1+1/3+1/5+...+1/2013) và B=1/2017(1/2+1/4+1/6+...+1/2014)
tính nhanh giá trị biểu thức
1-1/2+1/3-1/4+1/5-1/6+....+1/2011-1/2012
-------------------------------------------------------------
1006-1006/1007-1007/1008-1008/1009-...-2010/2011-2011/2012
---------- là phần nha
trình bày cách giải
Cho V = 1/1*2+1/3*4+1/5+6+...+1/2015*2016 và Y = 1/1008+1/1009+1/1010+...+1/2016.Tính V:Y
Sửa đề: Cho \(V=\frac{1}{1.2}+\frac{1}{3.4}+...+\frac{1}{2015.2016}\)và \(Y=\frac{1}{1009}+\frac{1}{1010}+...+\frac{1}{2016}\). Tính \(\frac{V}{Y}\)
\(V=\frac{1}{1.2}+\frac{1}{3.4}+...+\frac{1}{2015.2016}\)
\(=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2015}-\frac{1}{2016}\)
\(=\left(1+\frac{1}{3}+...+\frac{1}{2015}\right)-\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2016}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2016}\right)-2\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2016}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2016}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{1008}\right)\)
\(=\frac{1}{1009}+\frac{1}{1010}+...+\frac{1}{2016}\)
=> \(\frac{V}{Y}=\frac{\frac{1}{1009}+\frac{1}{1010}+...+\frac{1}{2016}}{\frac{1}{1009}+\frac{1}{1010}+...+\frac{1}{2016}}=1\)
V = \(\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{2015.2016}\)
V = \(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{2015}-\frac{1}{2016}\)
V = \(\left(1+\frac{1}{3}+\frac{1}{5}+...+\frac{1}{2015}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+...+\frac{1}{2016}\right)\)
V = \(\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{2015}+\frac{1}{2016}\right)-2.\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+...+\frac{1}{2016}\right)\)
V = \(\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2015}+\frac{1}{2016}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{1008}\right)\)
V = \(\frac{1}{1009}+\frac{1}{1010}+...+\frac{1}{2016}\)
Vậy V : Y = \(\frac{\frac{1}{1009}+\frac{1}{1010}+...+\frac{1}{2016}}{\frac{1}{1008}+\frac{1}{1009}+...+\frac{1}{2016}}\)
( Mình nghĩ Y = 1/1009 + 1/1010 + ... + 1/2016 / Nếu Y như mình nói thì V : Y = 1 )