JAMB Mathematics 2008 Objective — Question 22

Question 22 of 50 from the Joint Admissions and Matriculation Board (JAMB) Mathematics 2008 Objective paper, with the correct answer and a full explanation.

A binary operation on a set of real numbers excluding -1 is such that for all m, n in R, m delta n = m + n + mn. Find the identity element of the operation

A. 1
B. 0Correct
C. -1/2
D. -1

Explanation

KEY: The identity element of a given element combines with element to give still the element. m delta e = m + e + me. For the identity element e, we have m delta e = m + e + me = m, so e+me=0, e(1+m)=0, e=0/(1+m)=0. Thus the identity element is zero.

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