Question

$\ast$ is said to be commutative in $A$ for all $a,b\in A$

• A. $a+b=b+a$
• B. $a\ast b=b\ast a$
• C. $a-b=b-a$
• D. $a\ast b\ne b\ast a$

Answer 1

Answer: (B)

$a\ast b=b\ast a$

$\left(B\right)a\ast b=b\ast a$

here $\ast$ is commutative.