5x2 +12x +7 = 0
ax2 bx c = 0
a = 5
b = 12
c = 7
Δ = b2-4ac
Δ = 12² - (4 * 5 * 7)
Δ = 144 - (4*35)
Δ = 144 - (140)
Δ = 4 Δ > 0
5x2+12x+7=0
x = -b ∓ √Δ 2a
x' = -12 - √4 2*5 = -12 - 2.0 10 = -14.0 10 = -1.4
x" = -12 + √4 2*5 = -12 + 2.0 10 = -10.0 10 = -1.0
x' = -35.0
x" = -25.0
S = {x ∈ R / x' = -35.0, x" = -25.0 }