y = 2·x^2 - 3·x + 1
y = 2·(x^2 - 3/2·x) + 1
y = 2·(x^2 - 3/2·x + 9/16) + 1 - 9/8
y = 2·(x - 3/4)^2 - 1/8
D = [3/4 ; ∞[ ; W = [-1/8 ; ∞[
y + 1/8 = 2·(x - 3/4)^2
1/2·y + 1/16 = (x - 3/4)^2
± √(1/2·y + 1/16) = x - 3/4
3/4 ± √(1/2·y + 1/16) = x
x = 3/4 ± √(1/2·y + 1/16)
Umkehrfunktion
y = 3/4 ± √(1/2·x + 1/16)