the boolean operator ⊕, called the xor operator, is defined by 1 ⊕ 1 = 0, 1 ⊕ 0 = 1, 0 ⊕ 1 = 1, and 0 ⊕ 0 = 0. 24. simplify these expressions. a) x ⊕ 0 b) x ⊕ 1 c) x ⊕ x d) x ⊕ x