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2: 12-10x=25-30x
=>20x=13
=>x=13/20
3: \(3\left(2x+3\right)-2\left(4x-5\right)=10x+21\)
=>6x+9-8x+10=10x+21
=>10x+21=-2x+19
=>12x=-2
=>x=-1/6
4: \(\Leftrightarrow25x-15-6x+12=11-5x\)
=>19x-3=11-5x
=>24x=14
=>x=7/12
5: \(\Leftrightarrow8-12x-5+10x=4-6x\)
=>4-6x=-2x+3
=>-4x=-1
=>x=1/4
6: \(\Leftrightarrow32x-24-6+9x=13-40x\)
=>41x-30=13-40x
=>81x=43
=>x=43/81
7: \(\Leftrightarrow10x-5+20x=5x-11\)
=>30x-5=5x-11
=>25x=-6
=>x=-6/25
\(A=\dfrac{1}{3}x+x-\dfrac{4}{3}x=0\)
Do đó: Khi x=2011/2012 thì A=0
\(\frac{x-1}{3}+\frac{3x-5}{2}+\frac{2x}{9}+\frac{-5x+3}{9}=\frac{210}{420}\)
\(\Leftrightarrow\frac{x-1}{3}+\frac{3x-5}{2}+\frac{-3x+3}{9}=\frac{1}{2}\)
\(\Leftrightarrow\frac{6\left(x-1\right)}{18}+\frac{9\left(3x-5\right)}{18}+\frac{2\left(-3x+3\right)}{18}=\frac{9}{18}\)
\(\Rightarrow6x-6+27x-45-6x+6=9\)
\(\Leftrightarrow6x+27x-6x=9+6+45-6\)
\(\Leftrightarrow27x=54\)
\(\Rightarrow x=2\)
1) 3x - 6= 5x + 2
5x - 3x = -6 - 2
2x = -8
x = -4
2) 15 - x = 4x - 5
4x + x = 15 + 5
5x = 20
x = 4
Tương tự như trên
\(\dfrac{x-1}{3}\)+\(\dfrac{3x-5}{2}+\dfrac{2x}{9}+\dfrac{-5x+3}{9}=\dfrac{210}{420}\)
\(\Leftrightarrow\)\(\dfrac{x-1}{3}+\dfrac{3x-5}{2}\)\(+\dfrac{-3x+3}{9}\)\(=\dfrac{1}{2}\)
\(\Leftrightarrow\dfrac{6\left(x-1\right)}{18}+\dfrac{9\left(3x-5\right)}{18}\)\(+\dfrac{2\left(-3x+3\right)}{18}=\dfrac{9}{18}\)
\(\Rightarrow\)\(6x-6+27x-45-6x+6=9\)
\(\Leftrightarrow\)\(6x+27x-6x=9+6+45-6\)
\(\Leftrightarrow27x=54\)
\(\Rightarrow\)\(x=2\)
`(x-1)/3+(3x-5)/2+(2x)/9+(-5x)/9`
`=(x-1)/3+(3x-5)/2+x/3`
`=(2x-2+9x-15+2x)/6`
`=(13x-17)/6`
cảm ơn bạn nhiều^^