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

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

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

<=> -80x = -480

<=> x = \(\dfrac{-480}{-80}=6\)

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

⇔ 4.18 - 4.5x - 12.3x - 12.( - 7 ) = 15.2x - 15.16 - 6.x - 6.14

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

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

⇔ 80x = 480 ⇔ x = 6.

Vậy giá trị x cần tìm là x = 6.

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

⇔ 4.18 - 4.5x - 12.3x - 12.( - 7 ) = 15.2x - 15.16 - 6.x - 6.14

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

⇔ 80x = 480 ⇔ x = 6.

Vậy giá trị x cần tìm là x = 6.

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

\(\Rightarrow80x=480\Rightarrow x=6\)

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

\(\Rightarrow4x=0\Rightarrow x=0\)

c) \(\Rightarrow10x-16-12x+15=12x-16+11\)

\(\Rightarrow14x=4\Rightarrow x=\dfrac{2}{7}\)

Giải:

Ta có:

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

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

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

\(\Leftrightarrow-80x=-480\Leftrightarrow x=6\)

Vậy \(x=6\)

nhân vào bình thường thôi mà bạn....

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

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

<=> 156 - 56x = 24x - 324 <=> 80x = 480 <=> x= 6

Vậy..............

Ta có:

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

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

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

=>-80x=-480

=>x=6

Vậy: x=6

Chúc học tốt !tràn thị trúc oanh

Ta có

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

ó 72 – 20x – 36x + 84 = 30x – 240 – 6x – 84

ó -56x + 156 = 24x – 324

ó 24x + 56x = 156 +324 ó 80x = 480 ó x = 6

Vậy x = 6

Đáp án cần chọn là: C

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 '-'

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 = -240 - 84 - 72 -84 

-80x = -480

x= 6

4.(18 - 5x) - 12.(3x - 7) = 15.(2x - 16) - 6.(x+14)
4.18 - 4.5x - 12.3x + 12.7 = 15.2x - 15.16 - 6x - 6.14
72 - 20x - 36x + 84 = 30x - 240 - 6x - 84
72 + 84 - 20x - 36x = 30x - 6x - 240 - 84
156 - 56x               = 24x - 324
156                        = 24x - 324 + 56x
156                       = 80x - 324
80x - 324               = 156
80x                       = 156 + 324
80x                       = 480
x                           = 480:80

x                           = 6
câu b giải tương tự  

\(4\left(18-5x\right)-12\left(3x-7\right)-15\left(2x-16\right)-6\left(x+14\right)=0\\ \Leftrightarrow72-20x-36x+84-30x+240-6x-84=0\\ \Leftrightarrow\left(-20x-36x-30x-6x\right)+\left(72+84+240-84\right)=0\\ \Leftrightarrow-92x+312=0\\\Leftrightarrow-92x=-312\\ \Leftrightarrow x=\frac{-312}{-92}=\frac{78}{23} \)

Vậy pt có tập nghiệm \(S=\left\{\frac{78}{23}\right\}\)

4(18 - 5x) - 12(3x - 7) - 15(2x - 16) - 6(x + 14) = 0

<=> 72 - 20x - 36x + 84 - 30x + 240 - 6x - 84 = 0

<=> 312 - 92x = 0

<=> 92x = 312

<=> x = \(\frac{78}{23}\)

Vậy x = \(\frac{78}{23}\)

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 =