=>(-12x)-(-60)+21-7x=5

=>(-12x)+60+21-7x=5

=>(-12x-7x)=5-(60+21)=-76

=>(-19x)=-76=>x=4

Vậy x=4

-12(x-5)+7(3-x)=5

-12.x+12.5+7.3-7.x

-19x+60+21=5

-19x=-76

x=-76:(-19)=4

Vậy x=4

-12(x-5) + 7(3-x) =5 

( -12x + 60) + ( 21 - 7x) = 5

 -12x + 60 + 21 - 7x = 5

  -19x + 81 = 5

   -19x = 76

        x = -4

\(\Leftrightarrow-\dfrac{2}{5}\left(4x-3\right)^2=-\dfrac{5}{18}\)

\(\Leftrightarrow\left(4x-3\right)^2=\dfrac{25}{36}\)

\(\Leftrightarrow4x-3\in\left\{\dfrac{5}{6};-\dfrac{5}{6}\right\}\)

hay \(x\in\left\{\dfrac{23}{24};\dfrac{13}{24}\right\}\)

a) (2x - 3)(x + 1) - (5 + x)(2x - 4) = 10

<=> 2x² + 2x - 3x - 3 - (10x - 20 + 2x² - 4x) = 10

<=> 2x² - x - 3 - (2x² + 6x - 20) = 10

<=> 2x² - x - 3 - 2x² - 6x + 20 = 10

<=> -7x = -7 

<=> x = 1

Vậy x = 1 là nghiệm phương trình 

b) (x - 3)(x + 3) - (x + 1)² = 5

<=> x² - 9 - (x² + 2x + 1) = 5

<=> x² - 9 - x² - 2x - 1 = 5

<=> -2x = 15 

<=> x = -7,5

Vậy x = - 7,5 là nghiệm phương trình 

(5^x+4)(5^y+3) =516

=> 5^x+y+3.5^x+4.5^y+12=516

=> 5^x+y+3.5^x+4.5^y=504

VT không chia hết cho 5  Vì  VP = 504 không chia hết cho 5

Nên x=0 hoặc y =0

Nếu x =0   => PT: 5.5^y+15 =516 => 5^y+1=501 ( vô lí)

Nếu y=0 => PT: 4.5^x+16 =516 => 4.5^x =500 => 5^x =5³ => x =3

Vậy x=3; y=0

Bạn sai rồi nha, phải là \(5^{x+y}+4\cdot5^x+3\cdot5^y+3\)

`(2 2/5 + 3/5 x) = 3/4`

`=> 12/5 + 3/5 x = 3/4`

`=> 3/5 x= 3/4 - 12/5`

`=> 3/5 x= -33/20`

`=> x= -33/20 : 3/5`

`=> x=-11/4`

Vậy `x= -11/4`

2. ( x-3 ) + 3. (x+5) > 16

x = 7/5

\(-5\left(2-x\right)+4\left(x-3\right)=10x-15.\)

\(\Leftrightarrow-10+5x+4x-12=10x-15\)

\(\Leftrightarrow5x+4x-10x=10+12-15\)

\(\Leftrightarrow-x=7\)

\(\Rightarrow x=-7\)

         \(-5\left(2-x\right)+4\left(x-3\right)=10x-15\)

\(\Leftrightarrow-10+5x+4x-12-10x+15=0\)

\(\Leftrightarrow-x-7=0\)

\(\Leftrightarrow-x=7\)

\(\Leftrightarrow x=-7\)

~HOK TỐT~

\(\dfrac{3}{x+2}\)=\(\dfrac{5}{2x+1}\)(x khác -1/2 và x khác -2)

=>6x+3=5x+10

<=>x=7 tm 

x/2-x/6-17/3=12-5

3x/6-x/6-17/3=7

2x/6-17/3=7

2x/6=7+17/3

2x/6=38/3

x/3=38/3

=>x=38

vậy x=38

2x là 2 nhân x nhe

k mk nha

Mk cảm ơn bn nha!

\(\frac{x}{2}+5-\left(\frac{x}{6}+\frac{17}{3}\right)=\)\(12\)

     \(\frac{x}{2}+5-\frac{x}{6}-\frac{17}{3}=12\)

     \(\frac{x}{2}-\frac{x}{6}+5-\frac{17}{3}=12\)

       \(\frac{x}{2}-\frac{x}{6}+\left(\frac{-2}{3}\right)=12\)

                   \(x.\frac{1}{2}-x.\frac{1}{6}=12-\left(\frac{-2}{3}\right)\)

                 \(x.\left(\frac{1}{2}-\frac{1}{6}\right)=12,\left(6\right)\)

                                 \(x.\frac{1}{3}=12,\left(6\right)\)

                                       \(x=12,\left(6\right):\frac{1}{3}\)

                                       \(x=38\)