Define current. Define one ampere of current. [2 MARKS]
For each binary operation * defined below, determine whether * is commutative or associative.
(i) On Z, define a * b = a − b
(ii) On Q, define a * b = ab + 1
(iii) On Q, define a * b
(iv) On Z+, define a * b = 2ab
(v) On Z+, define a * b = ab
(vi) On R − {−1}, define