Let X = R. Is each of the following relations in X reflexive, symmetric, and transitive? 1. Riy if and only if x - y = 0 or 2. 2. xR2y if and only if x - y = 0, 2, or -2. 3. x3y if and only if x - y is a rational number. 4. xRay if and only if ay is an irrational number or x - y = 0.