Which of the following binary operations is not commutative?
-
A.
(a * b = frac{1}{a} + frac{1}{b}) -
B.
(a * b = a + b – ab) -
C.
(a * b = 2a + 2b + ab) -
D.
(a * b = a – b + ab)
Correct Answer: Option D
Explanation
All other options given are commutative i.e. (a * b = b * a), except option D.
(a * b = a – b + ab)
(b * a = b – a + ba)
(a – b = -(b – a) neq b – a)