-6x2 +23x -15 = 0
ax2 bx c = 0
a = -6
b = 23
c = -15
Δ = b2-4ac
Δ = 23² - (4 * -6 * -15)
Δ = 529 - (4*90)
Δ = 529 - (360)
Δ = 169 Δ > 0
-6x2+23x-15=0
x = -b ∓ √Δ 2a
x' = -23 - √169 2*-6 = -23 - 13.0 -12 = -36.0 -12 = 3.0
x" = -23 + √169 2*-6 = -23 + 13.0 -12 = -10.0 -12 = 0.833333333333
x' = 108.0
x" = 30.0
S = {x ∈ R / x' = 108.0, x" = 30.0 }