Question

Giải phương trình (x + 3). (x+ 5) = (x+ 4). (2+ x)

Answer 1

`(x + 3)(x + 5) = (x + 4)(2 + x)`

`=> x^2 + 8x + 15 = x^2 + 6x + 8`

`=> 8x + 15 = 6x + 8`

`=> 8x - 6x = 8 - 15`

`=> 2x = -7`

`=> x = -7/2`

Vậy: `S={-7/2}`

Answer 2

(x+3) . (x+5) = (x+4) . (2 +x)

\(x^{2} + 3x + 5x + 15 = x^{2} + 4x + 2x + 8\)

\(x^{2} + 3x + 5x + 15 - x^{2} - 4x _ 2x - 8 =0\)

2x + 7 = 0

2x = -7

x= -7 : 2

x = -7/2

Answer 3

`(x + 3)(x + 5) = (x + 4)(x + 2)`
`x^2 + 8x + 15 = x^2 + 6x + 8`
`8x + 15 = 6x + 8`
`2x = -7`
`x= -7/2`