a) The optimal value of x: I would need specific information or an equation to provide an optimal value for x. Please provide the necessary details or equations related to x, and I will be able to assist you in finding its optimal value.
b) The epimal wative of y: It seems there might be a typo or missing information in the question. Could you please clarify what you mean by "epimal wative" of y? Once I have a better understanding of the term or additional information about y, I will be able to assist you further.