Let * be a binary operation on set Q of rational numbers given by $a*b=a+b +ab.$ The identity element is :
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 0
$a*b=a+b +ab$
for identity element $i$
$a*i=a=a+i+ai$
so $i+ai=0⇒i=0$ identity element