The identity element for the binary operation * defined on Q ~ {0} as
b ∈Q ~ {0}is
Given that, 
Let e be the identity element for * such that
a*e = e*a = a
Now, 
⇒ 
⇒ 2a = ae
⇒ e = 2
34
The identity element for the binary operation * defined on Q ~ {0} asb ∈Q ~ {0}is
Given that,
Let e be the identity element for * such that
a*e = e*a = a
Now,
⇒
⇒ 2a = ae
⇒ e = 2