5x2 +8x -13 = 0
ax2 bx c = 0
a = 5
b = 8
c = -13
Δ = b2-4ac
Δ = 8² - (4 * 5 * -13)
Δ = 64 - (4*-65)
Δ = 64 - (-260)
Δ = 324 Δ > 0
5x2+8x-13=0
x = -b ∓ √Δ 2a
x' = -8 - √324 2*5 = -8 - 18.0 10 = -26.0 10 = -2.6
x" = -8 + √324 2*5 = -8 + 18.0 10 = 10.0 10 = 1.0
x' = -65.0
x" = 25.0
S = {x ∈ R / x' = -65.0, x" = 25.0 }