tim x
1/x+2015+1/x+2017+1/x-2018=1/3x+2015
K
Khách
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Những câu hỏi liên quan
8 tháng 7 2017
\(\frac{x+2015}{5}+\frac{x+2016}{4}=\frac{x+2017}{3}+\frac{x+2018}{2}\)
\(\Leftrightarrow\left(\frac{x+2015}{5}+1\right)+\left(\frac{x+2016}{4}+1\right)=\left(\frac{x+2017}{3}+1\right)+\left(\frac{x+2018}{2}+1\right)\)
\(\Leftrightarrow\frac{x+2020}{5}+\frac{x+2020}{4}-\frac{x+2020}{3}-\frac{x+2020}{2}=0\)
\(\Leftrightarrow\left(x+2020\right)\left(\frac{1}{5}+\frac{1}{4}-\frac{1}{3}-\frac{1}{2}\right)=0\)
\(\Leftrightarrow x+2020=0\)vì \(\frac{1}{5}+\frac{1}{4}+\frac{1}{3}+\frac{1}{2}\ne0\)
\(\Leftrightarrow x=-2020\)
2 tháng 9 2019
=> (x+2020)/5=(x+2020)/6=(x+2020)/3+(x+2020)/2
=>(x+2020)(1/5+1/6)=(x+2020)(1/3+1/2)
Với x+2020=0=>x=-2020
Với x+2020 khác 0=>1/5+1/6=1/3+1/2 ,vô lí
Vậy x=-2020
LV
0
Q
0
5 tháng 5 2017
Ta có: \(N\left(x\right)=x^{2017}-2018x^{2016}+2018x^{2015}-...-2018x^2+2018x-1\)
\(=x^{2017}-2018\left(x^{2016}-x^{2015}+...+x^2-x\right)-1\)
\(\Rightarrow N\left(2017\right)=2017^{2017}-2018\left(2017^{2016}-2017^{2015}+...+2017^2-2017\right)-1\)
Đặt \(A=2017^{2016}-2017^{2015}+...+2017^2-2017\)
\(\Rightarrow2017A=2017^{2017}-2017^{2016}+...+2017^3-2017^2\)
\(\Rightarrow2018A=2017^{2017}-2017\)
\(\Rightarrow A=\dfrac{2017^{2017}-2017}{2018}\)
\(\Rightarrow N\left(2017\right)=2017^{2017}-2018.\dfrac{2017^{2017}-2017}{2018}-1\)
\(=2017^{2017}-\left(2017^{2017}-2017\right)-1\)
\(=2017^{2017}-2017^{2017}+2017-1\)
\(=2016\)
Vậy N(2017) = 2016
TC
1
30 tháng 7 2018
\(\frac{x+4}{2018}+\frac{x+5}{2017}+\frac{x+6}{2016}+\frac{x+7}{2015}=-4\)
\(\Rightarrow\left(\frac{x+4}{2018}+1+\frac{x+5}{2017}+1+\frac{x+6}{2016}+1+\frac{x+7}{2015}+1\right)=-4+4=0\)
\(\Rightarrow\frac{x+2022}{2018}+\frac{x+2022}{2017}+\frac{x+2022}{2016}+\frac{x+2022}{2015}=0\)
\(\Rightarrow\left(x+2022\right)\left(\frac{1}{2018}+\frac{1}{2017}+\frac{1}{2016}+\frac{1}{2015}\right)=0\)
\(\Rightarrow x+2022=0\Leftrightarrow x=-2022\)
TN
Tìm \(x\varepsilonℝ\) biết \(\frac{x+1}{2018}+\frac{x+2}{2017}+\frac{x+3}{2016}=\frac{3x+12}{2015}\)
2
KY
10 tháng 5 2018
\(\dfrac{x+1}{2018}+\dfrac{x+2}{2017}+\dfrac{x+3}{2016}=\dfrac{3x+12}{2015}\)
\(\Rightarrow\dfrac{x+1}{2018}+\dfrac{x+2}{2017}+\dfrac{x+3}{2016}-\dfrac{3x+12}{2015}=0\)
\(\Rightarrow\dfrac{x+1}{2018}+\dfrac{x+2}{2017}+\dfrac{x+3}{2016}+\dfrac{3\cdot\left(x+4\right)}{2015}=0\)
\(\Rightarrow\left(\dfrac{x+1}{2018}+1\right)+\left(\dfrac{x+2}{2017}+1\right)+\left(\dfrac{x+3}{2016}+1\right)+\left(\dfrac{3}{2015}\cdot\left(\dfrac{x+4}{2015}+1\right)\right)=0\)
\(\Rightarrow\left(x+2019\right)\cdot\left(\dfrac{1}{2018}+\dfrac{1}{2017}+\dfrac{1}{2016}+\left(\dfrac{3}{2015}\cdot\dfrac{1}{2005}\right)\right)=0\)
\(\Rightarrow x+2019=0\\ \Rightarrow x=-2019\)
