a) \(2x\left(3x+1\right)+3x\left(4-2x\right)=7\)

\(\Rightarrow6x^2+2x+12x-6x^2=7\)

\(\Rightarrow14x=7\Rightarrow x=\frac{1}{2}\)

b) \(4\left(18-5x\right)-12\left(3x-7\right)=15\left(2x-16\right)-6\left(x+14\right)\)

\(72-20x-36x+84=30x-240-6x-84\)

\(\Rightarrow-20x-36x-30x+6x=-240-84-72-84\)

\(-80x=-480\)

x = 6

c) \(\left(3x+2\right).\left(2x+9\right)-\left(x+2\right).\left(6x+1\right)=\left(x+1\right)-\left(x-6\right)\)

\(\Rightarrow6x^2+4x+27x+18-6x^2-12x-x-2=x+1-x+6\) ( chỗ này bn tự phân tích ik nha, mk chỉ đưa ra kp sau khi phân tích thôi, ko thì viết ra dài lắm)

\(\Rightarrow18x+16=7\)

18x = -9

x = -2

18x = 

a) 4( 18 - 5x ) - 12( 3x - 16 ) = 15( 2x - 16 ) - 6( x + 14 )

<=> 72 - 20x - 36x + 192 = 30x - 240 - 6x - 84

<=> -20x - 36x - 30x + 6x = -240 - 84 - 72 - 192

<=> -80x = -588

<=> x = -588/-80 = 147/20

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

<=> x² + 5x + 6 - ( x² + 3x - 10 ) = 6

<=> x² + 5x + 6 - x² - 3x + 10 = 6

<=> 2x + 16 = 6

<=> 2x = -10

<=> x = -5

c) -x( x + 3 ) + 2 = ( 4x + 1 )( x - 1 ) + 2x

<=> -x² - 3x + 2 = 4x² - 3x - 1 + 2x

<=> -x² - 3x - 4x² + 3x - 2x = -1 - 2

<=> -5x² - 2x = -3

<=> -5x² - 2x + 3 = 0

<=> -( 5x² + 2x - 3 ) = 0

<=> -( 5x² + 5x - 3x - 3 ) = 0

<=> -[ 5x( x + 1 ) - 3( x + 1 ) ] = 0

<=> -( x + 1 )( 5x - 3 ) = 0

<=> \(\orbr{\begin{cases}x+1=0\\5x-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-1\\x=\frac{3}{5}\end{cases}}\)

d) ( 2x + 3 )( x - 3 ) - ( x - 3 )( x + 1 ) = ( 2 - x )( 3x + 1 ) + 3 

<=> 2x² - 3x - 9 - ( x² - 2x - 3 ) = -3x² + 5x + 2 + 3

<=> 2x² - 3x - 9 - x² + 2x + 3 = -3x² + 5x + 2 + 3

<=> 2x² - 3x - x² + 2x + 3x² - 5x = 2 + 3 + 9 - 3

<=> 4x² - 6x = 11

<=> 4x² - 6x - 11 = 0

=> Vô nghiệm ( Lớp 8 chưa học nghiệm vô tỉ nên để vậy ) :))

vẫn làm được nha quỳnh !

\(4x^2-6x-11=0\)

\(< =>\left(4x^2-6x+\frac{9}{4}\right)-13\frac{1}{4}=0\)

\(< =>\left(2x-\frac{3}{2}\right)^2=\frac{53}{4}\)

\(< =>\orbr{\begin{cases}2x-\frac{3}{2}=\frac{\sqrt{53}}{2}\\2x-\frac{3}{2}=-\frac{\sqrt{53}}{2}\end{cases}}\)

\(< =>\orbr{\begin{cases}2x=\frac{3+\sqrt{53}}{2}\\2x=\frac{3-\sqrt{53}}{2}\end{cases}}\)

\(< =>\orbr{\begin{cases}x=\frac{3+\sqrt{53}}{4}\\x=\frac{3-\sqrt{53}}{4}\end{cases}}\)

:vc dcv ơi, lớp 8 chưa học số vô tỉ ớ nên cho PT đó vô nghiệm là đúng, cái j mà ko làm đc:)) haha ( pịt momx lại ko bị chửi mù chữ:)

a, \(4\left(18-5x\right)-12\left(3x-16\right)=15\left(2x-16\right)-6\left(x+14\right)\)

\(\Leftrightarrow72-20x-36x+192=30x-240-6x-84\)

\(\Leftrightarrow264-56x=24x-324\Leftrightarrow x=\frac{147}{20}\)

c, \(-x\left(x+3\right)+2=\left(4x+1\right)\left(x-1\right)+2x\)

\(\Leftrightarrow-x^2-3x+2=4x^2-4x+x-1+2x\)

\(\Leftrightarrow-x^2-3x+2=4x^2-x-1\)

\(\Leftrightarrow5x^2+2x-3=0\Leftrightarrow\left(x+1\right)\left(5x-3\right)=0\Leftrightarrow\orbr{\begin{cases}x=-1\\x=\frac{3}{5}\end{cases}}\)

a: \(\Leftrightarrow6x^2+2x+12x-6x^2=7\)

=>14x=7

hay x=1/2

b: \(\Leftrightarrow72-20x-36x+84=30x-240-6x-84\)

=>-56x+156=24x-324

=>-80x=-480

hay x=6

c: \(\Leftrightarrow6x^2+27x+4x+18-6x^2-x-12x-2=x+1-x+6=7\)

=>18x+16=7

=>18x=-9

hay x=-1/2

Noob ơi, bạn phải đưa vào máy tính ý solve cái là ra x luôn, chỉ tội là đợi hơi lâu

a, 4.(18 - 5x) - 12(3x - 7) = 15(2x - 16) - 6(x + 14) 

=> 72 - 20x - 36x + 84 = 30x - 240 - 6x - 84

=> (72 + 84) + (-20x - 36x) = (30x - 6x) + (-240 - 84) 

=> 156 -  56x = 24x - 324 

=>  24x + 56x = 324 + 156 

=> 80x = 480 

=> x = 480 : 80 =  6 

Vậy x = 6 

b, 5(3x + 5) - 4(2x - 3) = 5x + 3(2x + 12) + 1 

=> 15x + 25 - 8x + 12 = 5x + 6x + 36 + 1 

=> (15x - 8x) + (25 + 12) = 11x + 37 

=> 7x + 37 = 11x + 37 

=> 11x - 7x = 0 

=>  x = 0 

a: Ta có: \(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x^2+2\right)=15\)

\(\Leftrightarrow x^3+8-x^3-2x=15\)

\(\Leftrightarrow2x=-7\)

hay \(x=-\dfrac{7}{2}\)

b: Ta có: \(\left(x-2\right)^3-\left(x-4\right)\left(x^2+4x+16\right)+6\left(x+1\right)^2=49\)

\(\Leftrightarrow x^3-6x^2+12x-8-x^3+64+6\left(x+1\right)^2=49\)

\(\Leftrightarrow-6x^2+12x+56+6x^2+12x+6=49\)

\(\Leftrightarrow24x=-13\)

hay \(x=-\dfrac{13}{24}\)

Tìm số nguyên x, biết:
1) -16 + 23 + x = - 16

7+x=-16

    x=-16-7

    x=-23
2) 2x – 35 = 15

2x=15+35

2x=50

  x=50:2

  x=25
3) 3x + 17 = 12

3x=12-17

3x=-5

  x=-5/3
4) (2x – 5) + 17 = 6

2x-5=6-17

2x-5=-11

2x=-11+5

2x=-6

  x=-6:2

  x=-3
5) 10 – 2(4 – 3x) = -4

2(4-3x)=10-(-4)

2(4-3x)=14

4-3x=14:2

4-3x=7

3x=4-7

3x=-3

  x=-3:3

  x=-1
6) - 12 + 3(-x + 7) = -18

3(-x+7)=-18-(-12)

3(x+7)=-6

x+7=-6:3

x+7=-2

    x=-2-7

    x=-9

tự đi mà làm

a) \(4\left(18-5x\right)-12\left(3x-7\right)=15\left(2x-16\right)-6\left(x+14\right)\)

\(\Rightarrow72-20x-36x-84=30x-240-6x+84\)

\(\Rightarrow\left(72-84\right)-\left(20x+36x\right)=\left(30x-6x\right)-240+84\)

\(\Rightarrow-12-56=24x-56x\)

\(\Rightarrow-12+156=24x+56x\)

\(\Rightarrow144=80x\)

\(\Rightarrow x=144:80\)

\(\Rightarrow x=\frac{9}{5}\)

b) \(5\left(3x+5\right)-4\left(2x-3\right)=5x+3\left(2x+12\right)+1\)

\(\Rightarrow15x+25-8x+12=5x+6x+36+1\)

\(\Rightarrow15x+25-8x+12-5x-6x-36-1=0\)

\(\Rightarrow-4x=0\)

\(\Rightarrow-4.0\)

\(\Rightarrow x=0\)

à) bằng 1,8

b) bằng 0

a) 4(18 - 5x) - 12(3x - 7) = 15(2x - 16) - 6(x +14)

<=> 72 - 20x - 36x + 84 = 30x - 240 - 6x - 84

<=> -20x - 36x - 30x + 6x = -72 - 84 - 240 - 84

<=> -80x = -480

<=> x = 6

b) 5(3x + 5) - 4(2x - 3) = 5x + 3(2x + 12) + 1

<=> 15x + 25 - 8x + 12 = 5x + 6x + 36 + 1

<=> 15x - 8x - 5x - 6x = -25 - 12 + 36 + 1

<=> -4x = 0

<=> x = 0

CTV sai dấu rồi kìa '-'

3,26 + 4/5 =?

làm nhanh lên giúp mình nhé

3,26+4/5=3,26+0,8=3,34

K cho mình cái

\(2\left(5x-8\right)-3\left(4x-5\right)=4\left(3x-4\right)+11\)

\(\Leftrightarrow10x-16-12x+15=12x+16+11\)

\(\Leftrightarrow-2x-1=12x+27\Leftrightarrow-14x-28=0\Leftrightarrow x=-2\)