Respostas

  • Usuário do Brainly
2013-11-20T22:42:10-02:00
A ) x² -12x = 0
x (x - 12) = 0
x = 0
x = 12
B) -4x² +28x = 0
4x(- x +28 ) = 0
x=0
x = -28
C) x² -x - 30 = 51 - x
x² = 81
x = + 9 ou -9
D) (x - 5)² = 25 -9x
x² - 10x +25 = 25 - 9x
x² -x = 0
x( x - 1) = 0
x = 0
x = 1