108a + 18b + 3c = 9
16a + 4b + 2c = 2
6a + 4b + 2c = 5.5
2*I - 3*II und II - III
168·a + 24·b = 12
10·a = - 3.5
III:10
a = -0.35
168·(-0.35) + 24·b = 12
b = (12 - 168·(-0.35)) / 24 = 2.95
16·(-0.35) + 4·(2.95) + 2c = 2
c = (2 - 16·(-0.35) - 4·(2.95)) / 2 = -2.1
(-0.35) + 2.95 + (-2.1) + d = 16.75
d = 16.75 - (-0.35) - 2.95 - (-2.1) = 16.25
K(x) = -0.35x^3 + 2.95x^2 - 2.1x + 16.25