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Math Help - Quadratics

  1. #1
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    Quadratics

    Problems 35, 36, 47, and 48 I have been having some trouble with....

    35 and 36
    For B...i had to find the zeros with a calculator
    for part c, I had to find the zeros algebraically

    47 and 48
    i had to find the zeros and max and min with a calculator
    for 47, i am a little confused about the +- part....

    I do not know is I am doing these correctly...if someone could take a look at my work, it would be greatly appreciated


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  2. #2
    Member Jonboy's Avatar
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    on 35 and 36 the c's look good. that's all i have time to check.
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    Forum Admin topsquark's Avatar
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    47 looks good.

    Where's the second zero on 48? (Look on the +x side.) And don't understand why you can't find max's and min's on this one? (See below.)

    -Dan
    Attached Thumbnails Attached Thumbnails Quadratics-quartic.jpg  
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    How do I simplify part C on 36? would it be Sqrt(2)?
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    I get 2 for the second zero on 48...max: (-2.1915, 19.688)...min: (-1.938E-6, 5)
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    How do you know to use +-
    or just + or just minus for the zeros and extrema
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    I have another question, if maybe someone can help me
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  8. #8
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by aikenfan View Post
    How do I simplify part C on 36? would it be Sqrt(2)?
    No, watch your factoring:

    \frac{10 \pm \sqrt{200}}{10}

    = \frac{10 \pm \sqrt{2 \cdot 10^2}}{10}

    = \frac{10 \pm 10 \sqrt{2}}{10}

    = \frac{10(1 \pm \sqrt{2})}{10}

    1 \pm \sqrt{2}

    -Dan
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    Forum Admin topsquark's Avatar
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    Quote Originally Posted by aikenfan View Post
    I get 2 for the second zero on 48...max: (-2.1915, 19.688)...min: (-1.938E-6, 5)
    Check that zero. I'm getting it to be less than 2. (Or you might be rounding it off too severely.)

    And take a look at that graph again: I'm getting two relative maxima, not one. However, what you have listed is good. (Though you could probably round that -1.938 x 10^(-6) to 0 if you wanted.)

    -Dan
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  10. #10
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by aikenfan View Post
    How do you know to use +-
    or just + or just minus for the zeros and extrema
    I'm not sure what the question is? Do you have a specific example of a problem where you are confused?

    -Dan
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  11. #11
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by aikenfan View Post
    I have another question, if maybe someone can help me
    It would be best to start a new question in a new thread at this point, but go ahead! We're here to help.

    -Dan
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  12. #12
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    i get 1.93 now, for that second zero on 48, i see what i did wrong
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  13. #13
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    on 48, for the other maxima, i get: (.915, 5.646)
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  14. #14
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    I also forgot to simplify part c on 35.....i got 2 + or - sqrt(3)
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  15. #15
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by aikenfan View Post
    i get 1.93 now, for that second zero on 48, i see what i did wrong
    Quote Originally Posted by aikenfan View Post
    on 48, for the other maxima, i get: (.915, 5.646)
    Quote Originally Posted by aikenfan View Post
    I also forgot to simplify part c on 35.....i got 2 + or - sqrt(3)
    These all look good to me!

    -Dan
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