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TÌM X
1) (8x-3)(3x+2)-(4x+7)(x+4)=(2x+1)(5x-1)
2) $2x^2$+3 (x-1)(x+1)=5x(x+1)
3) (8-5x)(x+2)+4(x-2)(x+1)+2(x-2)(x+2)=0
4) 4(x-1)(x+5)-(x+2)(x+5)=3(x-1)(x+2)
5) (3x-5)(2x-1)-(x+2)(6x-1)=0
6) (x+2)($x^2$-2+4)-x($x^2$+2)=15
7) 4(18-5x)-2(3x-7)=15(2x-16)-6(x+14)
8) 5(3x+5)-4(2x+3)=5x+3(2x+12)+1
9) (x+2)(x+3)-(x-2)(x+5)=6
10) (3x+2)(2x+9)-(x+2)(6x+1)=(x+1)-(x-6)
11) 3(2x-1) (3x-1)-(2x-3)(9x-1)=0

 

[thinhrost1]

$(8x-3)(3x+2)-(4x+7)(x+4)=(2x+1)(5x-1)$

\Leftrightarrow $20x^2-16x-34=10x^2+3x-1$

\Leftrightarrow $10x^2-19x-33=0$

\Leftrightarrow $(10x+11)(x-3)=0$

...

 

[quynhsieunhan]

2[TEX]x^2[/TEX] + 3(x - 1)(x + 1) = 5x(x + 1)
\Leftrightarrow 2[TEX]x^2[/TEX] + 3([TEX]x^2[/TEX] - 1) = 5[TEX]x^2[/TEX] + 5x
\Leftrightarrow 5[TEX]x^2[/TEX] - 3 = 5[TEX]x^2[/TEX] + 5x
\Leftrightarrow 5x = -3
\Leftrightarrow x = [TEX]\frac{-3}{5}[/TEX]

 

[quynhsieunhan]

(8 - 5x)(x + 2) + 4(x - 2)(x + 1) + 2(x - 2)(x + 2) = 0
\Leftrightarrow -5[TEX]x^2[/TEX] - 2x + 16 + 4([TEX]x^2[/TEX] - x - 2) + 2([TEX]x^2[/TEX] - 4) = 0
\Leftrightarrow -5[TEX]x^2[/TEX] - 2x + 16 + 4[TEX]x^2[/TEX] - 4x - 8 + 2[TEX]x^2[/TEX] - 8 = 0
\Leftrightarrow [TEX]x^2[/TEX] - 6x = 0
\Leftrightarrow x = 0 hoặc x = 6

 

[congchuaanhsang]

2) $2x^2$+3 (x-1)(x+1)=5x(x+1)

\Leftrightarrow $2x^2+3(x^2-1)=5x(x+1)$

\Leftrightarrow $2x^2+3x^2-3-5x^2-5x=0$

\Leftrightarrow $5x+3=0$

\Leftrightarrow $x=\dfrac{-3}{5}$

 

[maytrang154]

9) (x+2)(x+3)-(x-2)(x+5)=6

\Leftrightarrow[TEX]{(}[/TEX] [TEX]{x^2+3x+2x+6}[/TEX][TEX]{)}[/TEX][TEX]{-}[TEX][/TEX]{(}[/TEX][TEX]{x^2+5x-2x-10}[/TEX][TEX]{)}[TEX][/TEX]{=}[/TEX][TEX]{6}[/TEX]

\Leftrightarrow[TEX]{x^2+5x+6-x^2-3x+10[/TEX][TEX]{=}[/TEX][TEX]{6}[/TEX]

\Leftrightarrow[TEX]{2x+16}[/TEX][TEX]{=}[/TEX][TEX]{6}[/TEX]

\Leftrightarrow[TEX]{2x}[/TEX][TEX]{=}[TEX][/TEX]{-10}[/TEX]

\Leftrightarrow[TEX]{x}[/TEX][TEX]{=}[/TEX][TEX]{-5}[/TEX]

 

[one_day]

11) $3(2x-1) (3x-1)-(2x-3)(9x-1)=0$
\Leftrightarrow $(6x-3)(3x-1)-18x^2+2x+27x-3=0$
\Leftrightarrow $18x^2-6x-9x+3-18x^2+2x+27x-3=0$
\Leftrightarrow $14x=0$
\Leftrightarrow $x=0$

 

[duchuy0405]

10) (3x+2)(2x+9)-(x+2)(6x+1)=(x+1)-(x-6)
<=>6x^2+27x+4x+18-(6x^2+x+12x+2)=x+1-x+6
<=>6x^2+27x+4x+18-6x^2-x-12x-2 = 7
<=>18x+16=7
<=>x=[FONT=&quot]$\dfrac{-1}{2}.$[/FONT]

 

[maivuongthuy]

Ý a) (8x- 3).(3x+2) - (4x+7).(x+4)= (2x+1).(5x-1)
<=> (8x- 3).(3x+2) - (4x+7).(x+4)- (2x+1).(5x-1)=0
<=> 24x^2+16x- 9x- 6- 4x^2 - 16x -7x -28- 10x^2 +2x-5x+1=0
<=> 10x^2 -19x -33=0
<=> 10x^2+11x -30x -33=0
<=> x.(10x +11) - 3.(10x+11)=0
<=> (x-3).(10x+11) =0
<=> x-3=0\Leftrightarrowx=3
và 10x+11=0\Leftrightarrowx=-11/10.
Vậy............

 

[duchuy0405]

4) 4(x-1)(x+5)-(x+2)(x+5)=3(x-1)(x+2)
<=>4x^2+16x-20-x^2-7x-10=3x^2+3x-6
<=>6x-24=0
<=>x=4

 

[thaolovely1412]

5) [TEX](3x-5)(2x-1)-(x+2)(6x-1)=0[/TEX]
[TEX]\Leftrightarrow 6x^2-13x+5-6x^2-11x+2=0[/TEX]
[TEX]\Leftrightarrow 7-24x=0[/TEX]
[TEX]\Leftrightarrow 24x=7[/TEX]
[TEX]\Leftrightarrow x=\frac{7}{24}[/TEX]