Question 21


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Jambmaths question: 

A binary operation $\otimes $defined on the set of integers is such that m$\otimes $n = m + n + mn for all integers m and n. Find the inverse of  –5 under this operation, if the identity element is 0

Jamb Maths Solution: 

$\begin{align}  & \text{Let the inverse be }x,\text{and the identity element }e=0 \\ & -5\otimes x=e \\ & -5\otimes x=0 \\ & -5+x-5x=0 \\ & -4x=-5 \\ & x=\tfrac{5}{4} \\\end{align}$

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