Find a counterexample to show that each of the statements is false. (a) Every month of the year has 30 or 31 days. (b) If n is an integer and n2 is divisible by 4, then n is divisible by 4. (c) For every positive integer x, x3 2X (d) Every positive integer can be expressed as the sum of the squares of two integers. (e) The multiplicative inverse of a real number x, is a real number y such that xy = 1 . Every real number has a multiplicative inverse