Question

Tìm \(x\), biết :

a) \(3x\left(12x-4\right)-9x\left(4x-3\right)=30\)

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

Answer 1

Bài giải:

a) 3x (12x - 4) - 9x (4x - 3) = 30

36x² – 12x – 36x² + 27x = 30

15x = 30

Vậy x = 2.

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

5x – 2x² + 2x² – 2x = 15

3x = 15

x =5

Answer 2

a) 3x (12x - 4) - 9x (4x - 3) = 30

36x² – 12x – 36x² + 27x = 30

15x = 30

Vậy x = 2.

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

5x – 2x² + 2x² – 2x = 15

3x = 15

x =5

Answer 3

a) 3x (12x - 4) - 9x (4x - 3) = 30

\(\Leftrightarrow\) 36x² - 12x - 36x² + 27x = 30

\(\Rightarrow\) 15x = 30

\(\Rightarrow\) x = 2

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

\(\Leftrightarrow\) 5x - 2x² + 2x² - 2x = 15

\(\Rightarrow\) 3x = 15

\(\Rightarrow\) x = 5

Answer 4

a) 3x(12x-4)-9x(4x-3)=30

\(\)36x²-12x-36x²+27x=30

36x²-36x²-12x+27x=30

15x=30

x=2

Answer 5

a) 3x (12x-4)-9x(4x-3)=30

36x²-12x-36x²+27x = 30

15x = 30

Vậy x = 2

Answer 6

a) 3x (12x - 4) - 9x (4x - 3) = 30

=> 36x² – 12x – 36x² + 27x = 30

=> 15x = 30

=> x = 2

Vậy x = 2.

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

=> 5x – 2x² + 2x² – 2x = 15

=> 3x = 15

=> x = 5

Vậy x = 5.