passwella.
Menu

JAMB Mathematics 1978 Question 16

Question 16

Binary Operations

Given that a*b = ab + a + b and that a°b = a + b + 1, find an expression (not involving * or °) for (a*b)°(a*c) if a, b, c, are real numbers and the operations on the right are ordinary addition and multiplication of numbers.

  1. A.ac + ab + bc + b + c + 1
  2. B.ac + ab + a + c + 2
  3. C.ab + ac + a + b + 1
  4. D.ac + bc + ab + b + c + 2
  5. E.ab + ac + 2a + b + c + 1
Show the answer and explanation

Answer: E (ab + ac + 2a + b + c + 1)

Explanation

a*b = ab + a + b and a*c = ac + a + c. Joining them with ° adds them and adds 1: ab + ac + 2a + b + c + 1.