2x + 3 - 9x = -11
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PT
5
11 tháng 6 2017
\(2x^4-9x^3+14x^2-9x+2=0\)
\(\Leftrightarrow2x^4-4x^3+2x^2-5x^3+10x^2-5x+2x^2-4x+2=0\)
\(\Leftrightarrow2x^2\left(x^2-2x+1\right)-5x\left(x^2-2x+1\right)+2\left(x^2-2x+1\right)=0\)
\(\Leftrightarrow\left(2x^2-5x+2\right)\left(x^2-2x+1\right)=0\)
\(\Leftrightarrow\left(2x^2-x-4x+2\right)\left(x^2-2x+1\right)=0\)
\(\Leftrightarrow\left[x\left(2x-1\right)-2\left(2x-1\right)\right]\left(x^2-2x+1\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(2x-1\right)\left(x^2-2x+1\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x-1\right)^2\left(2x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x-1=0\\2x-1=0\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=2\\x=1\\x=\dfrac{1}{2}\end{matrix}\right.\)
Q
11 tháng 6 2017
\(2x^4-9x^3+14x^2-9x+2=0\)
\(\Leftrightarrow2x^4-2x^3-7x^3+7x^2+7x^2-7x-2x+2=0\)
\(\Leftrightarrow2x^3\cdot\left(x-1\right)-7x^2\cdot\left(x-1\right)+7x\cdot\left(x-1\right)-2\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(2x^3-7x^2+7x-2\right)=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left[2\left(x^3-1\right)-7x\cdot\left(x-1\right)\right]=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left[2\left(x-1\right)\cdot\left(x^2+x+1\right)-7x\cdot\left(x-1\right)\right]=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left(x-1\right)\cdot\left[2\left(x^2+x+1\right)-7x\right]=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left(x-1\right)\cdot\left(2x^2+2x+2-7x\right)=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left(x-1\right)\cdot\left(2x^2-5x+2\right)=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left(x-1\right)\cdot\left(2x^2-x-4x+2\right)=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left(x-1\right)\cdot\left[x\cdot\left(2x-1\right)-2\left(2x-1\right)\right]=0\)
\(\Leftrightarrow\left(x-1\right)\cdot\left(x-1\right)\cdot\left(x-2\right)\cdot\left(2x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)^2\cdot\left(x-2\right)\cdot\left(2x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(x-1\right)^2=0\\x-2=0\\2x-1=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=1\\x=2\\x=\dfrac{1}{2}\end{matrix}\right.\)
Vậy \(x_1=\dfrac{1}{2};x_2=1;x_3=2\)
DN
1
NT
1
31 tháng 5 2017
1,=> 36x^2-12x-36x^2+27x=30
=>15x =30
=> x =2
2,=>5x-2x^2+2x^2-2x=15
=>3x =15
=>x =5
PH
5
TH
5 tháng 3 2020
\(ĐKXĐ:x\ne2\)
\(\frac{9x^2}{x^3-8}+\frac{6}{x^2+2x+4}=\frac{3}{x-2}\)
\(\Leftrightarrow\frac{9x^2}{x^3-8}+\frac{6\left(x-2\right)}{x^3-8}=\frac{3\left(x^2+2x+4\right)}{x^3-8}\)
\(\Rightarrow9x^2+6x-12=3x^2+6x+12\)
\(\Leftrightarrow9x^2-3x^2+6x-6x-12-12=0\)
\(\Leftrightarrow6x^2-24=0\)
\(\Leftrightarrow6\left(x^2-4\right)=0\)
\(\Leftrightarrow x^2-4=0\)
\(\Leftrightarrow x^2=4\)
\(\Leftrightarrow x=\pm2\) (loại x = 2)
vậy x = -2
5 tháng 3 2020
\(\frac{9x^2}{x^3-8}+\frac{6}{x^2+2x+4}=\frac{3}{x-2}\)
=>\(\frac{9x^2}{x^3-8}+\frac{6\left(x-2\right)}{x^3-8}-\frac{3\left(x^2+2x+4\right)}{x^3+8}=0\)
=>\(9x^2+6x-12-3x^2-6x-24=0\)
=>\(6x^2-36\)\(6x^2-6\)
=>\(\left(6x-6\right)\left(6x+6\right)\)
=> \(6\left(x-1\right)6\left(x+1\right)\)
=>\(\orbr{\begin{cases}x=1\\x=-1\end{cases}}\)
#kenz
CT
2
2 tháng 1 2022
Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:
\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{2x-y}{2\cdot3-5}=11\)
Do đó: x=33; y=55
KB
15 tháng 9 2018
a ) \(4x\left(5x+2\right)-\left(10x-3\right)\left(2x+7\right)=133\)
\(\Leftrightarrow20x^2+8x-\left(20x^2-6x+70x-21\right)=133\)
\(\Leftrightarrow20x^2+8x-20x^2+6x-70x+21=133\)
\(\Leftrightarrow-56x+21=133\)
\(\Leftrightarrow-56x=112\)
\(\Leftrightarrow x=-2\)
Vậy \(x=-2\)
b ) \(3\left(6x-5\right)\left(4x+1\right)-\left(8x+3\right)\left(9x-2\right)=203\)
\(\Leftrightarrow\left(18x-15\right)\left(4x+1\right)-\left(72x^2+27x-16x-6\right)=203\)
\(\Leftrightarrow72x^2-60x+18x-15-72x^2-27x+16x+6=203\)
\(\Leftrightarrow\left(72x^2-72x^2\right)+\left(18x+16x-60x-27x\right)-\left(15-6\right)=203\)
\(\Leftrightarrow-53x-9=203\)
\(\Leftrightarrow-53x=212\)
\(\Leftrightarrow x=-4\)
Vậy \(x=-4\)
3 tháng 11 2017
5/9 - 11/9x=2/3-15/9x
5/9-2/3=(-15/9+11/9)x
-1/9=-4/9x
-1/9:-4/9=x
1/4=x
vậy1/4=x
BA
30 tháng 7 2019
\(\left|2x-\frac{1}{2}\right|+1=3x\)
\(\Leftrightarrow\left|2x-\frac{1}{2}\right|=3x-1\)
\(\Leftrightarrow\orbr{\begin{cases}2x-\frac{1}{2}=3x-1\\2x-\frac{1}{2}=1-3x\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}2x-3x=-1+\frac{1}{2}\\2x+3x=1+\frac{1}{2}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}-x=-\frac{1}{2}\\5x=\frac{3}{2}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=\frac{3}{10}\end{cases}}\)
2x+3- 9x = -11
=> 3-11x = -11
=> -11x = 3--11
=> -11x= 14
=> x= \(\frac{-14}{11}\)