Algebra


  1. If   x = √3 + √2, then the value of x +
    1
    is :
    x









  1. View Hint View Answer Discuss in Forum

    x = √3 + √2

    1
    =
    1
    x3 + √2

    =
    3 - √2
    (√3 + √2)(√3 - √2)

    = √3 - √2
    ∴ x +
    1
    x

    = √3 + √2 + √3 - √2 = 2√3

    Correct Option: B

    x = √3 + √2

    1
    =
    1
    x3 + √2

    =
    3 - √2
    (√3 + √2)(√3 - √2)

    = √3 - √2
    ∴ x +
    1
    x

    = √3 + √2 + √3 - √2 = 2√3


  1. If   x −
    1
    = 5, then x2 +
    1
      is
    xx2









  1. View Hint View Answer Discuss in Forum

    x −
    1
    = 5
    x

    On squaring both sides,
    x2 +
    1
    − 2 = 25
    x2

    ⇒  x2 +
    1
    = 27
    x2

    Second Method :
    Here,   x −
    1
    = 5
    x

    We know that
    x2 +
    1
    = x −
    1
    2 + 2
    x2x

    = 52 + 2 = 27

    Correct Option: C

    x −
    1
    = 5
    x

    On squaring both sides,
    x2 +
    1
    − 2 = 25
    x2

    ⇒  x2 +
    1
    = 27
    x2

    Second Method :
    Here,   x −
    1
    = 5
    x

    We know that
    x2 +
    1
    = x −
    1
    2 + 2
    x2x

    = 52 + 2 = 27



  1. One of the factors of the expression 4√3x2 + 5x − 2√3 is :









  1. View Hint View Answer Discuss in Forum

    4√3x² + 5x – 2√3
    = 4√3 x² + 8x – 3x – 2√3
    = 4x (√3x + 2) - √3( √3x + 2)
    = (4x - √3) (√3 + 2) ⇒ factors

    Correct Option: D

    4√3x² + 5x – 2√3
    = 4√3 x² + 8x – 3x – 2√3
    = 4x (√3x + 2) - √3( √3x + 2)
    = (4x - √3) (√3 + 2) ⇒ factors


  1. If   a2 – 4a – 1 = 0, then value of   a2 +
    1
    + 3a –
    3
      is
    a2a









  1. View Hint View Answer Discuss in Forum

    a² – 4a – 1 = 0
    ⇒ a² – 1 = 4a
    On dividing by a, we have

    a -
    1
    = 4
    a

    ∴ a² +
    1
    + 3a -
    1
    a

    = a -
    1
    ² + 2 + 3a -
    1
    aa

    = 16 + 2 + 3 (4) = 30

    Correct Option: B

    a² – 4a – 1 = 0
    ⇒ a² – 1 = 4a
    On dividing by a, we have

    a -
    1
    = 4
    a

    ∴ a² +
    1
    + 3a -
    1
    a

    = a -
    1
    ² + 2 + 3a -
    1
    aa

    = 16 + 2 + 3 (4) = 30