Question
The binary operation * is defined by a * b = a2 + b2 + ab + 1, then (2 * 3) * 2 is equal to:
  1. 20
  2. 40
  3. 400
  4. 445

Answer

  1. 445

Solution:

Given: a * b = a2 + b2 + ab + 1

2 * 3 = 22 + 32 + 2 × 3 + 1

= 4 + 9 + 6 + 1

= 20

(2 * 3) * 2 = 20 * 2

= 202 + 22 + 20 × 2 + 1

= 400 + 4 + 40 + 1

= 445

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