The Total solution for NCERT class 6-12
Find the identity element in the set I+ of all positiveintegers defined by a * b = a + b for all a, b ∈ I+.
Let e be the identityelement in I+ with respect to * such that
a * e = a = e * a, ∀ a ∈ I+
a * e = a and e * a =a, ∀ a ∈ I+
a + e = a and e + a =a, ∀ a ∈ I+
e = 0, ∀ a ∈ I+
Thus, 0 is theidentity element in I+ with respect to *.