Resposta:
x² - x - 6 = 0
a = 1 ; b = -1 ; c = -6
∆ = (-1)² - 4 × 1 × (-6)
∆ = 1 + 24
∆ = 25
X1/2 = -(-1) ± √25 / 2×1
X 1/2 = 1 ± 5 / 2
X1 = 1 - 5/2 = -4/2
X1 = -2
X2 = 1+5/2 = 6/2 = 3
S : {-2;3}
