Question

2x (3x + 9 )- 10 (3x +9) = 0

Answer 1

2x.(3x+9) - 10.(3x+9) = 0

(3x+9).(2x-10) = 0

=> 3x + 9 = 0 => 3x = -9 => x = -3

2x -10 = 0 => 2x = 10 =>  x=  5

KL:...

Answer 2

\(\Leftrightarrow\left(3x+9\right)\left(2x-10\right)=0\)

\(\Leftrightarrow6\left(x+3\right)\left(x-5\right)=0\)

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

Vậy ...

Answer 3

2x (3x + 9) - 10 (3x +9) = 0

(3x + 9) (2x - 10) = 0

3 (x + 3) 2 (x - 5) = 0

x + 3 = 0 hay x - 5 = 0

x = -3 hay x = 5