Respostas

2013-09-12T09:59:05-03:00
4x² - 57 = -21
4
x² - 57 + 21 = 0
4
x² - 15 = 0
4
x² = 15
x² = 15
        4
x = 3,75
2013-09-12T10:00:27-03:00
4x²= -21+57
4x² = 36
x² = 36/4
x² = 9
x = raiz de 9
x = 3