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Mathematics

If x2 - 2x - 3 = 0; values of x correct to two significant figures are :

  1. 3.0 and 1.0

  2. -1.0 and 3.0

  3. 3.0 or -1.0

  4. 3.00 or -1.00

Quadratic Equations

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Answer

Given,

⇒ x2 - 2x - 3 = 0

⇒ x2 - 3x + x - 3 = 0

⇒ x(x - 3) + 1(x - 3) = 0

⇒ (x + 1)(x - 3) = 0

⇒ x + 1 = 0 or x - 3 = 0

⇒ x = -1 or x = 3.

Rounding off to two significant figures, we get :

⇒ x = -1.0 or x = 3.0

Hence, Option 3 is the correct option.

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