Surds and Indices


  1. The value of -
    1
    - (2/3)
    125









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    The value of -
    1
    - (2/3)
    125

    =
    1
    -
    1
    - (2/3)
    125

    2
    = (- 125)3

    Correct Option: B

    The value of -
    1
    - (2/3)
    125

    =
    1
    -
    1
    - (2/3)
    125

    2
    = (- 125)3

    = [ ( - 125 )1/3 ]2 = [ (–5 × –5 × –5 )1/3 ]2
    = (–5)2 = – 5 × – 5 = 25


  1. If 102/5 × 108/5 = 10n, the value of n is :









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    ∵ 102/5 × 108/5 = 10n
    ⇒ 102/5 + 8/5 = 10n
    ⇒ 1010/5 = 10n

    Correct Option: A

    ∵ 102/5 × 108/5 = 10n
    ⇒ 102/5 + 8/5 = 10n
    ⇒ 1010/5 = 10n ⇒ 102 = 10n ⇒ n = 2
    Hence, the value of n is 2.



  1. The value of ( 8 ) - ( 2 - 2 ) is :









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    ( 8 ) - ( 2 - 2 ) =

    -
    1
    84

    =
    1
    1
    84

    =
    1
    1
    ( 2 x 2 x 2)4

    Correct Option: B

    ( 8 ) - ( 2 - 2 ) =

    -
    1
    84

    =
    1
    1
    84

    =
    1
    1
    ( 2 x 2 x 2)4

    =
    1
    3
    24

    -
    3
    = 24


  1. The positive exponential function of
    a-3 a-4
    is :
    a-5









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    a-3 a-4
    a-5

    =
    a5
    =
    a5
    a3 a4a7

    =
    1
    =
    1
    a7 - 5a2

    Correct Option: D

    a-3 a-4
    a-5

    =
    a5
    =
    a5
    a3 a4a7

    =
    1
    =
    1
    a7 - 5a2

    Therefore, positive exponential function of
    a-3 a-4
    will be
    1
    a - 5a2



  1. The expression
    ( - 1 )132
    is equivalent to :
    5- 1 + 3- 1









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    The expression
    ( - 1 )132
    is equivalent to:
    5- 1 + 3- 1

    =
    [( - 1 )2]66
    5- 1 + 3- 1

    =
    ( 1 )66
    5- 1 + 3- 1

    =
    1
    1
    +
    1
    53

    =
    1
    5 + 3
    15

    Correct Option: C

    ( - 1 )132
    5- 1 + 3- 1

    =
    [( - 1 )2]66
    5- 1 + 3- 1

    =
    ( 1 )66
    5- 1 + 3- 1

    =
    1
    1
    +
    1
    53

    =
    1
    5 + 3
    15

    =
    1
    8
    15

    =
    15
    8