Respostas

2014-08-30T16:08:14-03:00
A) 7x² - 21 = 0
x(7x - 21) = 0 → x= 0 1° raiz | 2° raiz 7x - 21= 0
x = 21/7 = 3
b) x² + 9 = 0 → x(x + 9) = 0 → 1° raiz x= 0 | 2° raiz
x = -9
c) x² - 49 = 0 → x(x - 49) = 0 → 1° raiz x= 0
2° raiz x - 49 = o → x = 49

2014-08-30T19:17:37-03:00