A binary operation * is defined on the set X = {1, 2, 3, 4, 5, 6} as a*b = ab + a + b. Compute 1 * 3
A
14
B
4
C
7
D
5
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
To compute 1 * 3 using the given binary operation * where a * b = ab + a + b:
Substitute a = 1 and b = 3 into the formula:
1 * 3 = (1)(3) + 1 + 3 = 3 + 1 + 3 = 7.
Thus, 1 * 3 = 7.
Source: WAEC / JAMB / NECO Classroom Archive (Record #74200)