WAEC - Further Mathematics (2011 - No. 1)
A binary operation * is defined on the set of real numbers R, by a* b = -1. Find the identity element under the operation *.
-1
0
1
2
คำอธิบาย
\(a * a^{-1} = e = -1\)
\(\therefore a^{-1} = -1\)
\(a * a^{-1} = e = -1\)
\(\therefore a^{-1} = -1\)