-1x2 +7x -12 = 0
ax2 bx c = 0
a = -1
b = 7
c = -12
Δ = b2-4ac
Δ = 7² - (4 * -1 * -12)
Δ = 49 - (4*12)
Δ = 49 - (48)
Δ = 1 Δ > 0
-x2+7x-12=0
x = -b ∓ √Δ 2a
x' = -7 - √1 2*-1 = -7 - 1.0 -2 = -8.0 -2 = 4.0
x" = -7 + √1 2*-1 = -7 + 1.0 -2 = -6.0 -2 = 3.0
x' = 4.0
x" = 3.0
S = {x ∈ R / x' = 4.0, x" = 3.0 }