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Math Help - function simple ....but the answer not logic for me

  1. #1
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    Thumbs down function simple ....but the answer not logic for me

    1. Given set A = {9, 36, 49, 64} and set B = {-8, -6, 3, 4, 6, 7, 8}. The relation from set A
    to set B is "the square root of ", state

    (a) the range of the relation,

    (b) the object of 8,

    (c) the image of 49.
    [ 3 marks ]

    ans given:

    a) {3,6,7,8} ---- my ans { 8,7,6,3,-6,-8}
    b) 56 ---- my ans 64
    c) 7 ---- my ans 7 (logic)

    hope i can get help

    below is my arrow diagrame:


    and the calculation of mapping as below

    calculation "the square root of "

    (a) the square root of 9 is +3 or -3 (-3 ignore)

    (b) the square root of 36 is +6 or -6

    (c) the square root of 49 is 7 or -7 (-7 ignore)

    (c) the square root of 64 is +8 or -8
    Last edited by nikk; March 27th 2008 at 12:30 PM. Reason: add picture
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  2. #2
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    Quote Originally Posted by nikk View Post
    1. Given set A = {9, 36, 49, 64} and set B = {-8, -6, 3, 4, 6, 7, 8}. The relation from set A
    to set B is "the square root of ", state
    (a) the range of the relation,
    (b) the object of 8,
    (c) the image of 49.
    ans given:
    a) {3,6,7,8} ---- my ans { 8,7,6,3,-6,-8}
    b) 56 ---- my ans 64
    c) 7 ---- my ans 7 (logic)
    I agree with the given answers for parts a) & c).
    There may be others who disagree with my using the convention that "the square root of " refers to a single non-negative number. But your text seems to be using that convention.

    I do not know what your text means by ‘object’.
    If it is what is usually called ‘pre-image’ then I agree with your answer 64.
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  3. #3
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    Quote Originally Posted by Plato View Post
    I agree with the given answers for parts a) & c).
    There may be others who disagree with my using the convention that "the square root of " refers to a single non-negative number. But your text seems to be using that convention.

    I do not know what your text means by ‘object’.
    If it is what is usually called ‘pre-image’ then I agree with your answer 64.
    tq mr ploto for your help & opinion ...

    it mean you consider +ve ans not the -ve ans????

    but i still have some new confusing here..is it this statement is correct or not

    the relation from set A to set B is "the square root of "

    is it logic
    (a) 9 is "the square root of " 3
    (b)36 is "the square root of " + 6 or -6
    and etc..... base on the mapping of set A to Set B??

    so for me may be the question should be
    set A = {-8, -6, 3, 4, 6, 7, 8}
    set B = {9, 36, 49, 64}

    instate of the original question
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  4. #4
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    Is English a second language for you? If so this confusion is completely understandable.
    5 is the square root of 25.
    25 is the square of both 5 and –5.
    But again,
    the convention is: "the square root of a number " refers to a single non-negative number whose square is the number.
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  5. #5
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    Talking

    Quote Originally Posted by Plato View Post
    Is English a second language for you? If so this confusion is completely understandable.
    5 is the square root of 25.
    25 is the square of both 5 and –5.
    But again,
    the convention is: "the square root of a number " refers to a single non-negative number whose square is the number.

    hai mr ploto tq very much for helping me....now i understand

    i already study this:
    Numbers - Square Roots - First Glance

    Numbers - Square Roots - In Depth

    Numbers - Square Roots - Examples

    Decimals and Integers - Square Roots - Workout
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