logo

CuriousTab

CuriousTab

Discussion


Home Aptitude Quadratic Equation Comments

  • Question
  • If x = ? ?(5 + 1)/?(5 - 1), then x 2 - x - 1 is equal to


  • Options
  • A. 0
  • B. 1
  • C. 2
  • D. 5

  • Correct Answer


  • Explanation

    Here, x = ??5 + 1/?5 - 1
    On rationalising the terms given in square root, we get
    x = ??5 + 1/?5 - 1 x ?5 + 1/?5 + 1
    ?5 + 1/2
    Now, substituting the value of x in x2 - x - 1.
    ? x2 - x - 1 = (?5 + 1/2)2 - (?5 + 1/2) - 1
    = 5 + 1 + 2?5/4 - ?5 + 1/2 - 1
    = 6 + 2?5 - 2?5 - 2 - 4 /4 = 0


  • Quadratic Equation problems


    Search Results


    • 1. 
      Two students A and B solve an equation of the from x 2 + px + q = 0. A starts with a wrong value of p and obtains the roots as 2 and 6. B starts with a wrong value of q and gets the roots as 2 and -9. What are the correct roots of the equation?

    • Options
    • A. 3 and - 4
    • B. - 3 and - 4
    • C. - 3 and 4
    • D. 3 and 4
    • Discuss
    • 2. 
      If one of the roots of the equation x 2 - bx + c = 0 is the square of the other, then which of the following option is correct?

    • Options
    • A. b3 = 3bc + c2 + c
    • B. c3 = 3bc + b2 + b
    • C. 3bc = c3 + b2 + b
    • D. 3bc = c3 + b3 + b2
    • Discuss
    • 3. 
      In solving a problem, one student makes a mistake in the coefficient of the first degree term and obtain -9 and -1 for the roots. Another student makes a mistake in the constant term of the equation and obtains 8 and 2 for the roots. The correct equation was

    • Options
    • A. x2 + 10x + 9 = 0
    • B. x2 - 10x + 16 = 0
    • C. x2 - 10x + 9 = 0
    • D. None of the above
    • Discuss
    • 4. 
      If ? and ? are the roots of the equation 8x 2 - 3x + 27 = 0, find the value of (? 2/?) 1/3 + (? 2/?) 1/3

    • Options
    • A. 1/3
    • B. 1/4
    • C. 7/2
    • D. 4
    • Discuss
    • 5. 
      The sum of the roots of the equation x 2 + px + q = 0 is equal to the sum of their squares, then

    • Options
    • A. p2 - q2 = 0
    • B. p2 + q2 = 2q
    • C. p2 + p = 2q
    • D. q2 + q2 = 2p
    • Discuss
    • 6. 
      If ?, ? are the roots of the equation x2 - 5x + 6 = 0, construct a quadratic equation whose roots are
      1
      ,
      1
      .
      ?
      ?

    • Options
    • A. 6x2 + 5x - 1 = 0
    • B. 6x2 - 5x - 1 = 0
    • C. 6x2 - 5x + 1 = 0
    • D. 6x2 + 5x + 1 = 0
    • Discuss
    • 7. 
      Consider the equation px2 + qx + r = 0, where p, q, r are real. The roots are equal in magnitude but opposite in sign when :

    • Options
    • A. q = 0, r = 0, p ? 0
    • B. p = 0, qr ? 0
    • C. r = 0, pr ? 0
    • D. q = 0, pr ? 0
    • Discuss
    • 8. 
      The roots of the equation 4x - 3 × 2x × 22 + 32 = 0 would include :

    • Options
    • A. 1, 2 and 3
    • B. 1 and 2
    • C. 1 and 3
    • D. 2 and 3
    • Discuss
    • 9. 
      Find the value of k so that the sum of the roots of the equation 3x2 + (2x + 1)x - k - 5 = 0 is equal to the product of the roots :

    • Options
    • A. 4
    • B. 6
    • C. 2
    • D. 8
    • Discuss
    • 10. 
      ?. x 2 -24x + 144 = 0
      ?. y 2 ? 26y + 169 = 0

    • Options
    • A. 1
    • B. 2
    • C. 3
    • D. 4
    • Discuss


    Comments

    There are no comments.

Enter a new Comment