Question

Biết 4x(x-1)-3(x²-5)-x²=(x-3)-(x-6). Giá trị của x là:

A) 3

B) 4

C) 6

D) 7

Answer 1

\(\Leftrightarrow4x^2-4x-3x^2+15-x^2=x-3-x+6\)

=>-4x+15=3

=>-4x=-12

=>x=3

Answer 2

<=> \(4x^2-4x-3x^2+15-x^2=x-3-x+6\)

<=> \(-4x+15-x+3+x-6=0\)

\(-4x+12=0\)

=> x = 3

Answer 3

`4x(x-1) - 3(x^2 -5 ) -x^2 = (x-3)-(x-6)`

`<=> 4x^2 - 4x -3x^2 + 15 - x^2 = x-3-x+6`

`<=> (4x^2 -3x^2 -x^2) +15-4x = (x-x)+(6-3)`

`<=> 15-4x = 3`

`<=> 4x = 15 - 3 =12`

`<=> x =12/4 =3`

Vậy `x=3`

`=> A (đúng)`