-12x2 +20x -7 = 0
ax2 bx c = 0
a = -12
b = 20
c = -7
Δ = b2-4ac
Δ = 20² - (4 * -12 * -7)
Δ = 400 - (4*84)
Δ = 400 - (336)
Δ = 64 Δ > 0
-12x2+20x-7=0
x = -b ∓ √Δ 2a
x' = -20 - √64 2*-12 = -20 - 8.0 -24 = -28.0 -24 = 1.16666666667
x" = -20 + √64 2*-12 = -20 + 8.0 -24 = -12.0 -24 = 0.5
x' = 168.0
x" = 72.0
S = {x ∈ R / x' = 168.0, x" = 72.0 }