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If x is a solution of the equation 2 x + 1 - 2 x - 1 = 1 , x ≥ 1 2 , then 4 x 2 - 1 is equal to :

Options

  1. A3 4
  2. B1 2
  3. C2 2
  4. D2

Correct answer

A. 3 4

Step-by-step solution

2 x + 1 -   2 x - 1 = 1         . . . 1 ⇒ 2 x + 1 + 2 x - 1 - 2 4 x 2 - 1 = 1 ⇒ 4 x - 1 = 2 4 x 2 - 1 ⇒ 16 x 2 - 8 x + 1 = 16 x 2 - 4 ⇒ 8 x = 5 ⇒ x = 5 8 which satisfies equation 1 . So, 4 x 2 - 1 = 3 4

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