Đáp án:
$\text{Bài 2 : }$
$ a) (x+2)(x+4) - x(x+2) = 104$
$⇔ x² +4x +2x +8 - x² -2x = 104 $
$ ⇔ x² - x² +4x + 2x -2x = 104 - 8 $
$ ⇔ 4x = 96$
$⇔ x = 96 : 4 $
$⇔ x = 24$
$\text { Vậy x = 24 }$
$b) (x-1) (x+4) - x(x-1) = 308$
$⇔ x² +4x -x -4 - x² +x = 308 $
$ ⇔ x² - x² +4x -x +x = 308 +4 $
$ ⇔ 4x = 312$
$⇔ x = 312 : 4$
$⇔ x = 78$
$\text{Vậy x = 78 }$
$\text{Bài 1 : }$
$a) (x-1)(x+1) - x(x+1) = 35$
$⇔ x² +x -x -1 - x² -x = 35$
$⇔x² - x² +x -x -x = 35 +1 $
$⇔ -x = 36$
$⇔ x = -36$
$\text{Vậy x = -36}$
$b) (2x-5)(x-3) =2x² + 2004$
$⇔ 2x² -6x -5x +15 = 2x² + 2004$
$⇔ 2x² - 2x² -6x -5x = 2004 -15 $
$⇔ -11x = 1989$
$⇔ x = 1989 : (-11)$
$⇔ x = -\dfrac{1989}{11} $
$\text{Vậy x = -$\dfrac{1989}{11}$}$
