2023 · Q24
What is the HCF of 3²⁹ - 9 and 3³⁸ - 9?
Elementary MathematicsHCF and LCM
- A3⁹ - 1
- B3¹1 - 1
- C3¹1 - 3
- D3¹1 - 9
Explanation
Factor out 9: 3²⁹ − 9 = 9(3²⁷ − 1) and 3³⁸ − 9 = 9(3³⁶ − 1). Using HCF(3^m − 1, 3^n − 1) = 3^HCF(m,n) − 1 with HCF(27, 36) = 9 gives 9(3⁹ − 1) = 3¹¹ − 9 (D).