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\(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)
\(\text{⇔}48x^2-32x+5-48x^2-7+115x=81\)
\(\text{⇔}83x-2=81\)
\(\text{⇔}83x=83\)
\(\text{⇔}x=1\)
Vậy: x=1
Ta có: \(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)
\(\Leftrightarrow48x^2-12x-20x+5+3x-48x^2-7+112x=81\)
\(\Leftrightarrow83x=83\)
hay x=1
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)
\(\Leftrightarrow48x^2-32x+5+48x^2+115x-7=81\)
\(\Leftrightarrow83x=83\)
\(\Leftrightarrow x=1\)
\(\Leftrightarrow48x^2-12x-20x+5+3x-48x^2-7+112x=81\\ \Leftrightarrow83x=83\Leftrightarrow x=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Rút gọn vế trái:
VT = (12x – 5)(4x – 1) + (3x – 7)(1 – 16x)
= 12x.(4x – 1) + (–5).(4x – 1) + 3x.(1 – 16x) + (–7).(1 – 16x)
= 12x.4x+ 12x.(–1) + (–5).4x + (–5).(–1) + 3x.1 + 3x.(–16x) + (–7).1 + (–7).(–16x)
= 48x2 – 12x – 20x + 5 + 3x – 48x2 – 7 + 112x
= (48x2 – 48x2) + (– 12x – 20x + 3x + 112x) + (5 – 7)
= 83x – 2
Vậy ta có:
83x – 2 = 81
83x = 81 + 2
83x = 83
x = 83 : 83
x = 1.
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Rightarrow48x^2-32x+5-48x^2+115x-7=81\)
\(\Rightarrow83x=83\Rightarrow x=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
( 12x - 5 ) ( 4x -1 ) + ( 3x - 7 ) ( 1 - 16x ) = 81
48x2-12x-20x+5+3x-48x2-7+112x=81
83x-2=81
83x=83
x=1
Vậy x=1
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Leftrightarrow48x^2-12x-20x+5+3x-48x^2-7+112x=81\)
\(\Leftrightarrow-32x+115x=81+2\)
\(\Leftrightarrow83x=83\)
\(\Leftrightarrow x=1\)
Vậy \(x=1\)
~Chúc bạn học tốt~
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(12x-5)(4x-1)+(3x-7)(1-16x)=81
48x^2-12x-20x+5+3x-48x^2-7+112x=81
83x-2=81
83x=83
x=1
(12x-5)(4x-1)+(3x-7)(1-16x)=81
12x ( 4x- 1) - 5(4x-1) + 3x(1-16x) -7(1-16x) =81
12x . 4x -12x - 20x + 5 + 3x - 3x. 16x - 7 + 7.16x = 81
48x^2 -12x - 20x + 5 + 3x - 48x^2 - 7 + 112x = 81
(48x^2 - 48x^2) + (112x - 12x - 20x +3x) - ( 7 - 5) =81
83x = 81 + 2
83x =83
x=1
ht nha bạn
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#)Giải :
Câu 1 :
5x(1 - 2x ) - 3x ( x+18) = 0
<=> 5x - 10x^2 - 3x^2 - 54x = 0
<=> -13x^2 - 49x = 0
<=> x= 0 hoặc x = - 49/13
Vậy x có hai giá trị là 0 và - 49/13
(12x - 5) (4x - 1) + (3x - 7) (1 - 16x) = 81
=> 48x2 - 12x - 20x + 5 + 3x - 48x2 - 7 + 112x = 81
=> 83x = 83
=> x = 1