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 = 10.0 10 = 1.0
x" = 12 + √4 2*5 = 12 + 2.0 10 = 14.0 10 = 1.4
x' = 25.0
x" = 35.0
S = {x ∈ R / x' = 25.0, x" = 35.0 }