Q. Let * be the binary operation on the rational no. given by a*b = a+b+2ab, which is true ?
I * is commutative
II There is a rational no that is a * - identity
III Every rational no has a * - inverse
A) I only
B) II only
C) I , II only
D) I and III only
E) I II and III
I thought ans is E, but ans is C, can somebody explain ?