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1) 5(x - 2) + 27 = 4x - 8
=> 5x - 10 + 27 = 4x - 8
=> 5x + 17 = 4x - 8
=> 5x - 4x = -8 - 17
=> x = -25
2) 3(x + 1) + 2(x + 2) = -13
=> 3x + 3 + 2x + 4 = -13
=> 5x + 7 = -13
=> 5x = -13 - 7
=> 5x = -20
=> x = -20 : 5
=> x = -4
3) (2x + 4)(5 - x) = 0
=> \(\orbr{\begin{cases}2x+4=0\\5-x=0\end{cases}}\)
=> \(\orbr{\begin{cases}2x=-4\\x=5\end{cases}}\)
=> \(\orbr{\begin{cases}x=-2\\x=5\end{cases}}\)
Vậy ...
4) x2 - 3x = 0
=> x(x - 3) = 0
=> \(\orbr{\begin{cases}x=0\\x-3=0\end{cases}}\)
=> \(\orbr{\begin{cases}x=0\\x=3\end{cases}}\)
Vậy ...
5) x2 - 3x + 2 = 0
=> x(x - 3) = -2
=> x(x - 3) = 1 . (1 - 3)
=> x = 1
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\(x\) \(\times\) \(\dfrac{4}{5}\) = 15
\(x\) = 15 : \(\dfrac{4}{5}\)
\(x\) = \(\dfrac{75}{4}\)
\(\dfrac{12}{25}\) \(\times\) \(x\) = \(\dfrac{4}{10}\)
\(x\) = \(\dfrac{4}{10}\) : \(\dfrac{12}{25}\)
\(x\) = \(\dfrac{5}{6}\)
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a. \(\frac{-3}{2}-2x+\frac{3}{4}=-22\)2
=> \(-2x=-22+\frac{3}{2}-\frac{3}{4}\)
=> \(-2x=\frac{-85}{4}\)
=> \(x=\frac{-85}{4}:\left(-2\right)\)
=> \(x=\frac{85}{8}\)
b. \(\left(\frac{-2}{3}x-\frac{3}{5}\right).\left(\frac{3}{-2}-\frac{10}{3}\right)=\frac{2}{5}\)
=> \(\left(\frac{-2}{3}x-\frac{3}{5}\right).\frac{-29}{6}=\frac{2}{5}\)
=> \(\frac{-2}{3}x-\frac{3}{5}=\frac{2}{5}:\left(\frac{-29}{6}\right)\)
=> \(\frac{-2}{3}x-\frac{3}{5}=\frac{-12}{145}\)
=> \(\frac{-2}{3}x=\frac{-12}{145}+\frac{3}{5}\)
=> \(\frac{-2}{3}x=\frac{15}{29}\)
=> x = \(\frac{15}{29}:\frac{-2}{3}\)
=> x = \(\frac{-45}{58}\)
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=>3x(1-1/6)=3/4
=>3x=3/4:5/6=3/4*6/5=18/20=9/10
=>x=3/10
Đề là \(3x\left(\dfrac{1}{1}\times\dfrac{1}{2}+\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{4}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{1}{6}\right)=\dfrac{3}{4}?\)
`3x (1/1 \times 1/2 + 1/2 \times 1/3 + 1/3 \times 1/4 + 1/4 \times 1/5 + 1/5 \times 1/6) = 3/4`
\(3x\left(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}\right)=\dfrac{3}{4}\)
\(3x\left(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}\right)=\dfrac{3}{4}\)
\(3x\left(1-\dfrac{1}{6}\right)=\dfrac{3}{4}\)
\(3x\times\dfrac{5}{6}=\dfrac{3}{4}\)
`3x=3/4 \div 5/6`
`3x = 9/10`
`x = 9/10 \div 3`
`x = 3/10.`
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a ) 10 x X - 1 - 3 - 5 - 7 - ... - 19 = 2 + 4 + 6 + ... + 20
10 x X - 1 - 3 - 5 - 7 - ... - 19 = 110
10 x X - ( 1 + 3 + 5 + 7 + ... + 19 ) = 110
10 x X - 100 = 110
10 x X = 110 + 100
10 x X = 210
X = 210 : 10
X = 21
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a) 4 × (5 - x) = x
20 - 4x = x
x + 4x = 20
5x = 20
x = 20 : 5
x = 4
b) 1/2 (x - 14) = 2
x - 14 = 2 : 1/2
x - 14 = 4
x = 4 +14
x = 18
c) 18/13 + 3 × x = 3
3x = 3 - 18/13
3x = 21/13
x = 21/13 : 3
x = 7/13
d) đề khó hiểu
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ĐKXĐ: x^2-3x>=0 và 5(3-x)>=0
=>x(x-3)>=0 và 3-x>=0
=>x<=3 và (x<=0 hoặc x>=3)
=>x=3 hoặc x<=0
\(\sqrt{x^2-3x}-\sqrt{5\left(3-x\right)}=0\)
=>\(\sqrt{x^2-3x}=\sqrt{5\left(3-x\right)}\)
=>x^2-3x=5(3-x)
=>x(x-3)=-5(x-3)
=>(x-3)(x+5)=0
=>x=3 hoặc x=-5(nhận)
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a) 2.(5 +3 .x) + x =31
10 + 6.x + x = 31
6x + x = 31-10
7x = 21
x = 21:7
x=3
Vậy x=3
b) ( 3x -7 ) +2 . (5-2x) + 5x = 19
3x - 7 + 10 - 4x + 5x = 19
3x - 4x + 5x = 19 + 7 - 10
4x = 16
x = 16:4
x = 4
Vậy x=4
\(a,2\left(5+3x\right)+x=31\)
\(10+6x+x=31\)
\(10+7x=31\)
\(7x=21\)
\(x=3\)
\(b,\left(3x-7\right)+2\left(5-2x\right)+5x=19\)
\(3x-7+10-4x+5x=19\)
\(4x+3=19\)
\(4x=16\)
\(x=4\)
x-5=5/3:2/3
x-5=2,5
x=2,5+5
x=7,5
2/3 x ( x -5 ) = 5/3
x - 5 = 5/3 : 2/3
x - 5 = 5/2
x = 5/2 + 5
x = 15/2
Vay x = 15/2