Question

 x ao quadrado -7x+12 = 0

Answer 1

∆ = b² - 4 . a . c
∆ = 7² - 4 . 1 . 12
∆ = 49 - 48
∆ = 1

x = (-b ± √∆) / 2a
x = (-7 ± √1) / (2 . 1)
x = (-7 ± 1) / 2

x' = (-7 + 1) / 2
x' = -6 / 2
x' = -3

x" = (-7 - 1) / 2
x" = -8 / 2
x" = -4

S = {-4, -3}