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\(=\frac{2.3.4..2017}{1.2.3..2016}=\frac{2017}{1}=2017\)

28 tháng 2 2020

\(\frac{2}{1}\cdot\frac{3}{2}\cdot\frac{4}{3}\cdot\cdot\cdot\cdot\cdot\frac{2017}{2016}\)

\(=\frac{2\cdot3\cdot4\cdot\cdot\cdot\cdot\cdot2017}{1\cdot2\cdot3\cdot\cdot\cdot\cdot\cdot2016}\)

\(=\frac{2017}{1}=2017\)

2 tháng 8 2016

\(=\frac{3}{1}.\frac{4}{2}.\frac{5}{3}...\frac{2018}{2016}.\frac{2019}{2017}\\ =\frac{3.4.5...2018.2019}{1.2.3...2016.2017}\\ =\frac{2018.2019}{2}=1009.2019\)

22 tháng 6 2017

\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\cdot\cdot\cdot\cdot\cdot\frac{2016}{2017}\)

\(=\frac{1.2........2016}{2.3.............2017}\)

\(=\frac{1}{2017}\)

22 tháng 6 2017

a) \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(x-\frac{1}{4}\right).....\left(1-\frac{1}{2016}\right).\left(1-\frac{1}{2017}\right)\)

\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}......\frac{2015}{2016}.\frac{2016}{2017}=\frac{1}{2017}\)

20 tháng 8 2016

b)\(\left(2016.1017+2017.2018\right).\left(1+\frac{1}{2}:\frac{3}{2}-\frac{4}{3}\right)\)

\(\left(2016.2017+2017.2018\right)\left(1+\frac{1}{3}-\frac{4}{3}\right)\)

\(\left(2016.2017+2017.2018\right).\left(\frac{4}{3}-\frac{4}{3}\right)\)

\(\left(2016.2017+2017.2018\right).0\)

\(=0\)

20 tháng 8 2016

a) \(1001.789+456.128.128-789+912.436\)

\(=\left(1001.789-789\right)+\left(456.2.64.128+912.436\right)\)

\(=789.1000+912.4\left(2048+109\right)\)

\(=789000+912.4.2157\)

\(=8657736\)

24 tháng 8 2019

Ta có: \(\frac{x-2019}{2018}+\frac{x-2018}{2017}=\frac{x-2017}{2016}+\frac{x-2016}{2015}\)

\(\Leftrightarrow\left(\frac{x-2019}{2018}+1\right)+\left(\frac{x-2018}{2017}+1\right)=\left(\frac{x-2017}{2016}+1\right)+\left(\frac{x-2016}{2015}+1\right)\)

\(\Leftrightarrow\frac{x-1}{2018}+\frac{x-1}{2017}=\frac{x-1}{2016}+\frac{x-1}{2015}\)

\(\Leftrightarrow\frac{x-1}{2018}+\frac{x-1}{2017}-\frac{x-1}{2016}-\frac{x-1}{2015}=0\)

\(\Leftrightarrow\left(x-1\right)\left(\frac{1}{2018}+\frac{1}{2017}-\frac{1}{2016}-\frac{1}{2015}\right)=0\)

\(\Leftrightarrow x-1=0\)( vì \(\frac{1}{2018}+\frac{1}{2017}-\frac{1}{2016}-\frac{1}{2015}\ne0\))

\(\Leftrightarrow x=1\)

Vạy x=1

17 tháng 7 2017

=\(\frac{1}{2}x\frac{2}{3}x...x\frac{2017}{2018}\)

=\(\frac{1}{2018}\)

bạn trừ ra là đc

18 tháng 7 2017

\(\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot....\cdot\left(1-\frac{1}{2017}\right)\cdot\left(1-\frac{1}{2018}\right)\)

\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot...\cdot\frac{2016}{2017}\cdot\frac{2017}{2018}\)

\(=\frac{1\cdot2\cdot3\cdot....\cdot2016\cdot2017}{2\cdot3\cdot4\cdot....\cdot2017\cdot2018}\)

\(=\frac{1}{2018}\)

1 tháng 9 2020

\(=\left(\frac{1}{2}\right).\left(\frac{2}{3}\right).\left(\frac{3}{4}\right)....\left(\frac{2017}{2018}\right)\)

\(=\frac{1.2.3....2017}{2.3.4...2018}\)

\(=\frac{1}{2018}\)

1 tháng 9 2020

\(=\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot...\cdot\left(1-\frac{1}{2018}\right)\)  

\(=\frac{1}{2}\cdot\frac{2}{3}\cdot...\cdot\frac{2017}{2018}\)  

\(=\frac{1}{2018}\)

21 tháng 3 2017

bằng 15 hay sao ý