-9x2 +23x -10 = 0
ax2 bx c = 0
a = -9
b = 23
c = -10
Δ = b2-4ac
Δ = 23² - (4 * -9 * -10)
Δ = 529 - (4*90)
Δ = 529 - (360)
Δ = 169 Δ > 0
-9x2+23x-10=0
x = -b ∓ √Δ 2a
x' = -23 - √169 2*-9 = -23 - 13.0 -18 = -36.0 -18 = 2.0
x" = -23 + √169 2*-9 = -23 + 13.0 -18 = -10.0 -18 = 0.555555555556
x' = 162.0
x" = 45.0
S = {x ∈ R / x' = 162.0, x" = 45.0 }