-12x2 -x +13 = 0

ax2 bx c = 0

a = -12

b = -1

c = 13

Δ = b2-4ac

Δ = -² - (4 * -12 * 13)

Δ = 1 - (4*-156)

Δ = 1 - (-624)

Δ = 625      Δ > 0

-12x2-x+13=0

x = -b ∓ √Δ 2a

x' = 1 - √625 2*-12 = 1 - 25.0 -24 = -24.0 -24 = 1.0

x" = 1 + √625 2*-12 = 1 + 25.0 -24 = 26.0 -24 = -1.08333333333

x' = 144.0

x" = -156.0

S = {x ∈ R / x' = 144.0, x" = -156.0 }