Hello there I have a very small system of nonlinear equation and i do not quite understand how I can use this using Optim.jl. So far I have only figured out how to do one equation but I have a system (3 Equations):

The system is defined by:

```
function fb(x)
dco, dm, dcr = x*1e3
rco = dco
rm = dco + dm
rcr = dco + dm + dcr
ρco = 13e3 #kg/m^3
ρm = 4.5e3
ρcr = 2.9e3
R_planet = 6062e3 #m
M_planet = 4.88e24 #kg
C = 0.33*M_planet*R_planet^2
radius = dco + dcr + dm - R_planet
mass = 4/3*pi *( dco^3 * ρco + ((dco + dm)^3 - dm^3)*ρm + ρcr*((dco + dm + dcr)^3 - (dco + dm)^3)) - M_planet
MoI = 8/15*π*(ρco * rco^5 + ρm * (rm^5 - rco^5) + ρcr*(rcr^5 - rm^5)) - C
return [radius, mass, MoI]
end
```

How can I solve for possible solution vectors x with Optim.jl?

Also anyone know how to implement constraints?

Thank you in advance.