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प्रश्न
If * is defined on the set R of all real numbers by *: a*b =
उत्तर
Let * be an operation defined on R
a * b =
Let ‘e’ be the identity element
then a*e = e*a = a
B squaring on both side
e2 + a2 = a2
e2 = 0 ⇒ e = 0
a*0 =
i.e. if a = -2 (or any other negative real no.)
then a* 0 ≠ -2
since a*0 =
Hence identity element does not exists.
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