Tìm x , biết
1) x-1998 = 2002 2) x - 2012 = 2013 3) x : 18 = 25 4) x : 23 = 72
5) (135 + 2012).x=0 6) x.(1972 + 2013) = 0 7) x.(x-1) =0 8) (x-9).(x-15) = 0
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\(6x\left(1-3x\right)+9x\left(2x-7\right)+171=0\)
\(\Leftrightarrow6x-18x^2+18x^2-63x+171=0\)
\(\Leftrightarrow-57x=-171\)
\(\Leftrightarrow x=3\)
\(\frac{x+1}{2015}+\frac{x+2}{2014}=\frac{x+3}{2013}+\frac{x+4}{2012}\)
\(\Leftrightarrow\left(\frac{x+1}{2015}+1\right)+\left(\frac{x+2}{2014}+1\right)-\left(\frac{x+3}{2013}+1\right)-\left(\frac{x+4}{2012}+1\right)=0\)
\(\Leftrightarrow\)\(\frac{x+2016}{2015}+\frac{x+2016}{2014}-\frac{x+2016}{2013}+\frac{x+2016}{2012}=0\)
\(\Leftrightarrow\left(x+2016\right)\left(\frac{1}{2015}+\frac{1}{2014}-\frac{1}{2013}-\frac{1}{2012}\right)=0\)
\(\Leftrightarrow x+2016=0\) ( vì \(\frac{1}{2015}+\frac{1}{2014}-\frac{1}{2013}-\frac{1}{2012}\ne0\) )
\(\Leftrightarrow x=-2016\)
\(x_1+x_2+...+x_{2013}=0\)
=> \(\left(x_1+x_2\right)+\left(x_3+x_4\right)+...+\left(x_{2011}+x_{2012}\right)+x_{2013}=0\)
=> \(2+2+...+2+x_{2013}=0\)
=> \(2.1006+x_{2013}=0\Rightarrow2012+x_{2013}=0\Rightarrow x_{2013}=-2012\)
1) x-1998=2002
x=2002+1998
x=4000
2)x-2012=2013
x=2012+2013
x=4025
3)x:18=25
x=25.18
x=450
4)x:23=72
x=72.23
x=1656
5)(135+2012).x=0
x=0:(135+2012)
x=0
6)x.(1972+2013)=0
x=0:(1972+2013)
x=0
7)x.(x-1)=0
<=> x=0 hoặc x-1=0
x-1=0
x=0+1
x=1
Vậy x=1 hoặc 0
8) (x-9).(x-15)=0
<=> x-9=0 hoặc x-15=0
x-9=0
x=9
x-15=0
x=15
Vậy x=9 hoặc x=15
chúc bạn học tốt nha
1) X=4000 2)X=4025 3)X=450 4)X=1656 5)X=0 6) X=0 7)X=0 ,X=1 8)X=9,X=15