$\left(x-3x^2\right).\left(x+6\right)+x.\left(3x^2+17x\right)=24$

$\iff x^2+6x-3x^3-18x^2+x.\left(3x^2+17x\right)=24$

$\iff x^2+6x-3x^3-18x^2+3x^3+17x^2=24$

$\iff x^2+6x-18x^2+17x^2=24$

(x-3x² ) . (x + 6) + x . ( 3x² + 17x) = 24

<=> x² + 6x - 3x³ - 18x² + 3x³ + 17x²

<=> 6x = 24

<=> x = 24 : 6

<=> x = 4

1. is getting

2. are living

3. is happening

4. is having

5. isn't

6. aren't drinking

7. is composing

8. are having

$x.\left(5-2x\right)+2x.\left(x-1\right)=15$

$\iff 5x-2x^2+2x.\left(x-1\right)=15$

$\iff 5x-2x^2+2x^2-2x=15$

$\iff 5x-2x=15$

$\iff 3x=15$

$\iff x=15:3$

<=> x = 5

<=> 5x - 2x² + 2x² - 2x = 15

<=> 5x - 2x = 15

<=> 3x = 15

<=> x = 5

Vậy, phương trình có tập nghiệm S = {5}

x(5 - 2x) + 2x (x-1) = 15

<=> 5x - 2x² + 2x² - 2x = 15

<=> 3x = 15

<=> x = 15 : 3

<=> x = 5