Jawapan

2016-01-21T22:48:31+08:00
-x^2 - 12x + 9 = 0
x^2 + 12x - 9 = 0
x^2 + 12x = 9
x^2 + 12x + (12/2)^2 = 9 + (12/2)^2
x^2 + 12x + (6)^2 = 9 + 36
(x + 6)^2 = 45
x + 6 = √45
x + 6 = +-6.7082

x + 6 = 6.7082
x = 0.7082

x + 6 = -6.7082
x = -12.7082