Cho A=\(\left(\dfrac{1}{2}-1\right).\left(\dfrac{1}{3}-1\right).\left(\dfrac{1}{4}-1\right)...\left(\dfrac{1}{2015}-1\right).\left(\dfrac{1}{2016}-1\right).\left(\dfrac{1}{2017}-1\right)\)
B=\(\left(-1\dfrac{1}{2}\right).\left(-1\dfrac{1}{3}\right).\left(-1\dfrac{1}{4}\right)...\left(-1\dfrac{1}{2015}\right).\left(-1\dfrac{1}{2016}\right).\left(-1\dfrac{1}{2017}\right)\)
Tính M=A.B
Tìm x biết
\(\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2015}+\dfrac{1}{2016}\right)x=\dfrac{2015}{1}+\dfrac{2014}{2}+...+\dfrac{2}{2014}+\dfrac{1}{2015}\)
Tính :
A=\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{2015}+\dfrac{1}{2016}\)
\(Cho\) \(S=1-\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{5}-...+\dfrac{1}{2013}-\dfrac{1}{2014}+\dfrac{1}{2015}\)
\(B=\dfrac{1}{1008}+\dfrac{1}{1009}+\dfrac{1}{1010}+...+\dfrac{1}{2014}+\dfrac{1}{2015}\)
Tính (S - B)2016
tìm x biết (\(\dfrac{1}{2}\)+\(\dfrac{1}{3}\)+\(\dfrac{1}{4}\)+...+\(\dfrac{1}{2018}\)).x=\(\dfrac{2017}{1}+\dfrac{2016}{2}+\dfrac{2015}{3}+...+\dfrac{2}{2016}+\dfrac{1}{2017}\)
Cho
\(\dfrac{2016c-2017b}{2015}\)=\(\dfrac{2017a-2015c}{2016}\)=\(\dfrac{2015b-2016a}{2017}\).
Chứng minh \(\dfrac{a}{2015}\)=\(\dfrac{b}{2016}\)=\(\dfrac{c}{2017}\)
Cho \(\dfrac{a}{2015}=\dfrac{b}{2016}=\dfrac{c}{2017}\).Chứng minh rằng : 4(a-b)(b-c)=(c-a)2
a, CMR : nếu \(\dfrac{a}{b}=\dfrac{c}{d}\) thì \(\dfrac{5a+3b}{5a-3b}=\dfrac{5c+3d}{5c-3d}\) ( gt các tỉ số đều có nghĩa )
b, tìm x,biết: \(\dfrac{x-1}{2017}+\dfrac{x-2}{2016}+\dfrac{x-3}{2015}=\dfrac{x-4}{2014}\)
Tìm X \(\dfrac{x-1}{2017}+\dfrac{x-2}{2016}=\dfrac{x-3}{2015}+\dfrac{x-4}{2014}\)
