Question 22

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Jambmaths question: 

A binary operation on the set of real numbers excluding –1 is such  that, for all m, n $\varepsilon $ R, $m\Delta n=m+n+mn$. Find the identity element of the operation

Option A: 

1

Option B: 

0

Option C: 

$-\frac{1){2}$

Option D: 

-1

Jamb Maths Solution: 

$\begin{align}  & m\Delta n=m+n+mn \\ & m\Delta e=m+e+me=m\text{   (}e\text{ is the identity element)} \\ & e+me=0 \\ & e(1+m)=0 \\ & e=\frac{0}{1+m} \\ & e=0 \\\end{align}$

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