Question

4x^2-(2x+5)(2x-3)=7

Answer 1

\(\Leftrightarrow4x^2-4x^2+6x-10x+15=7\)

=>4x=-8

hay x=-2

Answer 2

`4x^2-(2x+5)(2x-3)=7`

`<=> 4x^2 - [ 2x(2x-3) + 5(2x-3) ] =7`

`<=> 4x^2 - [4x^2 -6x+10x -15] =7`

`<=> 4x^2 - 4x^2 +4x +15 =7`

`<=>4x +15 =7`

`=> 4x = 7-15 =-8`

`=> x =-8/4 =-2`

Vậy `S={-2}`