Hey, could anyone tell me what is the rule of that function?

Here are the numbers found in the table (numbers with periods are approximated by the original problem):

(x.y)

(0.100)

(1.100)

(2.90)

(3.85,86)

(4.82,68)

(6.77,63)

(8.73,54)

I already tried multiple times with a lot of different forms of fuctions but I didn't succeed into getting the right numbers out, even if I did get close with a square root function.