Respostas

2014-07-23T23:32:46-03:00
X² - 4x - 12 = 0

a = 1
b = -4
c = -12

b² - 4ac =

(-4)² - 4. 1 . (-12)

16 + 48 = 64

- b +- raiz64/2

- (-4) +- 8/2

4 +- 8/2

x' = 4 + 8/2 = 6
x" = 4 - 8/ 2 = -2



2014-07-23T23:40:41-03:00
X²-4x-12=0 
(-4x)²- 4.1.(-12)
16+48
64
x = -(- 4) +-   √¯64
              2.1
x = 4 +- 8
        2
x¹ = 4 + 8 = 12 = 6
          2        2
x² = 4 - 8 = - 4 = -2
          2       2
S = { -2, 6 }