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 }