Projectile motion with drag

[tejsa1]

I have got 4 differential equations I wanna solve with runga kutta 4. method:
v_x'=k*(x'² + y'²)^0.5 * x'
v_y'=k*(x'² + y'²)^0.5* y' - g
x' = v_x
y' = v_y

K = -0.02
g = 9.82
Where initial conditions:
v_x=5.74
v_y= 8.19
x = 0
y = 0

To solve this I will do:

I have made this to a spreadsheet: https://www.dropbox.com/sh/472jdrtlx...0s2pgs3Da?dl=0
But I solved it in maple too, but it gave me a completely different answer:


Can anyone see what I did wrong in my spreadsheet?