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A binary operation * is defined by a*b = ab+a+b for any real number a...

Mathematics
JAMB 1999

A binary operation * is defined by a*b = ab+a+b for any real number a and b. if the identity element is zero, find the inverse of 2 under this operation.

  • A. 2/3
  • B. 1/2
  • C. -1/2
  • D. -2/3
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Correct Answer: Option D
Explanation

\(a*a^{-1} = aa^{-1} + a + a^{-1} = e\)

if e = 0

\(2.2^{-1} + 2 + 2^{-1} = 0\)

collecting like terms, we have:
\(3.2^{-1} + 2 = 0\)

= \(2^{-1}\) = -\(\frac{2}{3}\)


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WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709