JAMB - Mathematics (1995 - No. 19)
Which of the following binary operations is cumulative on the set of integers?
a \(\ast\) b = a + 2b
a \(\ast\) b = a + b - ab
a \(\ast\) b = a2 + b
a \(\ast\) b = \(\frac{a(b + 1)}{2}\)
Uitleg
\(a \ast b = a + b - ab\)
\(b \ast a = b + a - ba\)
On the set of integers, the two above are cumulative as multiplication and addition are cumulative on the set of integers.