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A binary operation on the real set of numbers excluding -1 is such that for all m, n ...

A binary operation on the real set of numbers excluding -1 is such that for all m, n ∈ R, mΔn = m+n+mn. Find the identity element of the operation.
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  • A 1
  • B Zero
  • C -1/2
  • D -1
Correct Answer: Option B
Explanation:
mΔn = m+n+mn
Let e be the identity element
−mΔe = eΔm = m
m+e+me = m
e+me = m-m
e+me = 0
e(1+m) = 0
e = 0 / (1+m)
e = 0

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