Algebra


  1. If x = – 1, then the value of
    1
    +
    1
    +
    1
    +
    1
    +
    1
    +
    1
    +
    1
    - 1 is
    x99x98x97x96x95x94x










  1. View Hint View Answer Discuss in Forum

    On putting x = -1

    1
    =
    1
    = -1
    x99(-1)99

    1
    =
    1
    = 1
    x98(-1)98

    1
    =
    1
    = -1 and so on.
    x97(-1)97

    ∴ Expression = – 1 + 1 – 1 + 1 – 1 + 1 – 1 – 1 = – 2

    Correct Option: C

    On putting x = -1

    1
    =
    1
    = -1
    x99(-1)99

    1
    =
    1
    = 1
    x98(-1)98

    1
    =
    1
    = -1 and so on.
    x97(-1)97

    ∴ Expression = – 1 + 1 – 1 + 1 – 1 + 1 – 1 – 1 = – 2


  1. If a + b + c = 0, then a3 + b3 + c3 is equal to









  1. View Hint View Answer Discuss in Forum

    Using Rule 21,
    ∴ a3 + b3 + c3 – 3abc = (a + b + c)(a2 + b2 + c2 – ab – bc – ca)
    If a + b + c = 0, then a3 + b3 + c3 = 3abc

    Correct Option: D

    Using Rule 21,
    ∴ a3 + b3 + c3 – 3abc = (a + b + c)(a2 + b2 + c2 – ab – bc – ca)
    If a + b + c = 0, then a3 + b3 + c3 = 3abc



  1. If a + b + c = 0, then a3 + b3 + c3 is equal to









  1. View Hint View Answer Discuss in Forum

    Using Rule 21,
    ∴ a3 + b3 + c3 – 3abc = (a + b + c)(a2 + b2 + c2 – ab – bc – ca)
    If a + b + c = 0, then a3 + b3 + c3 = 3abc

    Correct Option: D

    Using Rule 21,
    ∴ a3 + b3 + c3 – 3abc = (a + b + c)(a2 + b2 + c2 – ab – bc – ca)
    If a + b + c = 0, then a3 + b3 + c3 = 3abc


  1. If a = 4.965, b = 2.343 and c = 2.622, then the value of a3 - b3 - c3 – 3abc is :









  1. View Hint View Answer Discuss in Forum

    Using Rule 21,
    If a + b + c = 0, then a3 + b3 + c3 = 3abc
    ∴ When a – b – c = 0,
    a3 - b3 - c3 = 3abc
    i.e. a3 - b3 - c3 - 3abc = 0
    Here,a = 4.965, b = 2.343, c = 2.6222
    ∴ a – b – c = 4.965 – 2.343 – 2.622 = 0
    Hence, a3 - b3 - c3 - 3abc = 0

    Correct Option: C

    Using Rule 21,
    If a + b + c = 0, then a3 + b3 + c3 = 3abc
    ∴ When a – b – c = 0,
    a3 - b3 - c3 = 3abc
    i.e. a3 - b3 - c3 - 3abc = 0
    Here,a = 4.965, b = 2.343, c = 2.6222
    ∴ a – b – c = 4.965 – 2.343 – 2.622 = 0
    Hence, a3 - b3 - c3 - 3abc = 0



  1. If a = 1.21, b = 2.12 and c = –3.33, then the value of a3 - b3 - c3 – 3abc is









  1. View Hint View Answer Discuss in Forum

    Using Rule 21,
    Here, a + b + c = 1.21 + 2.12 – 3.33 = 0
    a3 - b3 - c3 - 3abc = 0 ( ∴ a + b + c = 0)

    Correct Option: A

    Using Rule 21,
    Here, a + b + c = 1.21 + 2.12 – 3.33 = 0
    a3 - b3 - c3 - 3abc = 0 ( ∴ a + b + c = 0)