can a model be multi objective? what is objective functions used for? what is the way to optimize multiple objective functions why is this function used in the optimization how does constraint optimization works why are objective functions used as a constraint what is the optimization of multiple objective functions why is y1 optimization important what is the way to optimize multiple objective functions is y one objective function how to optimize multiple objective functions what is meant by the optimisation constraints a r optimize objective functions what are two objective functions that can be combined? which objective function would be used for optimization what is the optimization of multiple objective functions with constraints which equation is an objective function why are objective functions useful in r which model has multiple objective functions? what is y3