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JAMB Mathematics 1983 Question 34

Question 34

Algebraic Expressions

Factorize completely 81a4 − 16b4

  1. A.(3a + 2b)(2a − 3b)(9a2 + 4b2)
  2. B.(3a − 2b)(2a − 3b)(4a2 − 9b2)
  3. C.(3a − 2b)(3a + 2b)(9a2 + 4b2)
  4. D.(3a − 2b)(2a − 3b)(9a2 + 4b2)
  5. E.(3a − 2b)(2a − 3b)(9a2 − 4b2).
Show the answer and explanation

Answer: C ((3a − 2b)(3a + 2b)(9a2 + 4b2))

Explanation

81a⁴ − 16b⁴ = (9a² − 4b²)(9a² + 4b²), and 9a² − 4b² = (3a − 2b)(3a + 2b).