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KCET2011MathematicsQuadratic Equation

If , and are roots of x³-2 x+1=0 , then the value of ( 1 + - ) is

Options

  1. A- 1 2
  2. B-1
  3. C0
  4. D1 2

Correct answer

B. -1

Step-by-step solution

Given cubic x³-2 x+1=0,( , , ) are roots of this equation. Then, sum of roots =0 + + =0 =-2, =-1 Now, we have aligned 1 + - &= 1 - - =- 1 2 1 &=- 1 2 ( 1 + 1 + 1 ) &=- 1 2 ( + + ) aligned =- 1 2 =- 1 2 (-2) (-1) =-1

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