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Math Help - algebraic question

  1. #1
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    Lightbulb

    I have also another algebric quesion to ask. I found this equation EXTREMELY EASY, but many of my friends in the class don't know the ans. not even the smartest math guy in the class, he has a deformed head, he says that he studies too much and it goes weird. so heres the quesrtion.

    if x+z=y,
    and x+9(7-7)=y,
    what is z+x+y?
    I ansered x+y.
    (oh yeah, this has nothing to do with the previous question.)
    is this question really that difficult? and did i get the answer correct?? w the?
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  2. #2
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    Yes, x+y+z = x+y. ----one correct answer.

    Also,
    x+y+z = 2x ----another correct answer.
    x+y+z = 2y ----still another correct answer.

    Is the question really that difficult?
    No.
    In fact, it is really that easy.
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  3. #3
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    Exclamation

    Quote Originally Posted by ticbol
    Yes, x+y+z = x+y. ----one correct answer.

    Also,
    x+y+z = 2x ----another correct answer.
    x+y+z = 2y ----still another correct answer.

    Is the question really that difficult?
    No.
    In fact, it is really that easy.
    how did you get 2x abd 2y as answers?
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  4. #4
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    You figured correctly that z=0. That is why you got x+y+z = x+y.

    So if z=0,
    x+z=y,
    x+0 = y
    x = y ------***

    Then,
    x+y+z
    = x +y +0
    = x +y -----(1)

    But x=y,
    So, substitute that into (1),
    = y +y
    = 2y

    Also, since x=y, then y=x.
    So, substitute that into (1),
    = x +x
    = 2x

    -------------------------
    But why is z equal to zero?
    Did you guess that, or you found it?

    Anyway, this is why z=0.

    if x+z=y,
    and x+9(7-7)=y,
    what is z+x+y?

    x +9(7-7) = y
    x +9(0) = y
    x +0 = y
    x = y -----***
    Substitute that into "if x+z=y",
    x +z = y
    y +z = y
    z = y -y
    z = 0

    That is why.
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  5. #5
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    Lightbulb okay

    okay, thanks for your time
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