-12x2 +8x +7 = 0
ax2 bx c = 0
a = -12
b = 8
c = 7
Δ = b2-4ac
Δ = 8² - (4 * -12 * 7)
Δ = 64 - (4*-84)
Δ = 64 - (-336)
Δ = 400 Δ > 0
-12x2+8x+7=0
x = -b ∓ √Δ 2a
x' = -8 - √400 2*-12 = -8 - 20.0 -24 = -28.0 -24 = 1.16666666667
x" = -8 + √400 2*-12 = -8 + 20.0 -24 = 12.0 -24 = -0.5
x' = 168.0
x" = -72.0
S = {x ∈ R / x' = 168.0, x" = -72.0 }