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प्रश्न
Find which of the operations given above has identity.
उत्तर
An element e ∈ Q will be the identity element for the operation * if
a * e = a = e * a, ∀ a ∈ Q.
We are given
a * b = ab4
⇒ a*e = a⇒ae4=a⇒ e=4
Similarly, it can be checked for e*a=a, we get e=4 Thus, e = 4 is the identity
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