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JAMB Mathematics 1991 Question 12

Question 12

Algebraic Expressions

Multiply (x2 − 3x + 1) by (x − a)

  1. A.x3 − (3 + a) x2 + (1 + 3a) x − a
  2. B.x3 − (3 − a) x2 + 3ax − a
  3. C.x3 − (a − 3) x2 − (1 + 3a) − a
  4. D.x3 + (3 − a) x2 + (1 + 3a) − a
Show the answer and explanation

Answer: A (x3 − (3 + a) x2 + (1 + 3a) x − a)

Explanation

Expanding gives x3 − ax2 − 3x2 + 3ax + x − a. Grouping like terms: x3 − (3 + a)x2 + (1 + 3a)x − a.