Respostas

2014-05-20T20:54:39-03:00
(x + 5) · (x - 6) = 51 - x
x² - 6x + 5x - 30 = 51 - x
x² - 6x + 5x + x - 30 - 51 = 0
x² - 81 = 0
x² = 0 + 81
x² = 81
x = +√81
x = +9
S = {+9}