if x y are two random variable then e(x,y)

It seems like you're asking about the expectation of two random variables, denoted as E(X,Y). However, the expectation is typically defined for one random variable at a time, not for a pair of random variables.

If you're referring to the expected value of the product of two random variables, it would be denoted as E(XY). This is calculated by summing (or integrating, in the continuous case) the product of each possible pair of outcomes weighted by the probability of that pair occurring.

If you're referring to the joint expectation, it's important to note that the joint expectation E(X,Y) does not exist. Instead, you might be referring to the joint distribution, which describes the probability of events defined in terms of both X and Y.

If you're referring to the expectation of X given Y (or vice versa), it would be denoted as E(X|Y) (or E(Y|X)). This is the expected value of X when Y is known to be a certain value.

Without more context, it's hard to provide a more specific answer. Could you please provide more details?