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      Question

      If 8x2 + y2 βˆ’ 12x βˆ’ 4xy + 9 =

      0, then the value of (14x βˆ’ 5y) is :
      A 9 Correct Answer Incorrect Answer
      B 3 Correct Answer Incorrect Answer
      C 5 Correct Answer Incorrect Answer
      D 6 Correct Answer Incorrect Answer

      Solution

      8xΒ²+yΒ²-12x-4xy+9 = 0 8xΒ²+yΒ²-12x-4xy+9 = 0 (2x-y) Β² + (2x-3) Β² = 0 ∴ 2x-3 = 0 β‡’ x = 3/2 2x-y = 0 3-y = 0β‡’ y= 3 ∴ (14x-5y) = 14Γ— 3/2 βˆ’ 5 Γ— 3 = 21-15 = 6

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