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Math Help - Limits Question

  1. #1
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    Limits Question

    Hi, my question is this;



    My strategy is to take the limit as x->1 of the first relation, which yields 2.
    I then set the limit (x->1) ax^2 - bx + 5 = 2

    or

    a - b + 3 = 0 (1)

    Likewise, I take the limit as x->3 of the second and third relations.
    These two limits yield

    9a - 3b + 5 = 12 - a + b or

    10a -4b - 7 = 0 (2)

    I now have two equations and two unknowns so I solve for a = -19/6 and b = -37/6.

    What is wrong with this approach?

    Thanks.
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  2. #2
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    Quote Originally Posted by lampmad View Post
    Hi, my question is this;



    My strategy is to take the limit as x->1 of the first relation, which yields 2.
    I then set the limit (x->1) ax^2 - bx + 5 = 2

    or

    a - b + 3 = 0 (1)

    Likewise, I take the limit as x->3 of the second and third relations.
    These two limits yield

    9a - 3b + 5 = 12 - a + b or

    10a -4b - 7 = 0 (2)

    I now have two equations and two unknowns so I solve for a = -19/6 and b = -37/6.

    What is wrong with this approach?

    Thanks.
    change the signs for a and b
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  3. #3
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    Ok, can you explain why?
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  4. #4
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    Quote Originally Posted by lampmad View Post
    Ok, can you explain why?
    because you made a mistake in solving for a and b
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  5. #5
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    Oh, well then. lol thanks.
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