Question

Let R1 and R2 be relations on the set {1, 2, ….., 50} such that R1 ={(p, pn) : p is a prime and n≥ 0 is an integer} and R2 = {(p, pn) : p is a prime and n = 0 or 1}. Then, the number of elements in R1 – R2 is ______.

Answer 1

The number of elements in**** R1 – R2 = {(2, 22), (2, 23), (2, 24), (2, 25), (3, 32), (3, 33), (5, 52), (7, 72)}

So, the number of elements is 8.