I was solving some question papers and got stuck in this problem.
I know how to find "marginal probabilities" from a joint probability density function and also know how to find the covariance and independence.
But I am getting stuck in the range part while integration. While finding f(x1, x4) or f(x1) or during finding the covariance how do I integrate over the given range as I am not accustomed to handle such ranges as in here.(marked in red)
Please help me solve this.