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Math Help - quadratic homework help

  1. #1
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    quadratic homework help

    Hi all can you help, I have been asked to give answer in decimal to a quadratic formula. I have attached my workings, but Im not sure if my answers are correct, If I have made and error, can I get a pointer as to what I have done wrong...Many thanks.

    quadratic homework help-scan.jpg
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  2. #2
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    Re: quadratic homework help

    (11 + root97) / 2 = 10.4244289

    (11 - root97) / 2 = 0.5755710991
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  3. #3
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    Re: quadratic homework help

    thanks for the reply, I have just done it all again and the scientific calculator is giving me my origional answer,but a standard calculator give me your answers? lost
    Dave
    Last edited by davellew69; April 1st 2012 at 06:56 AM.
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  4. #4
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    Re: quadratic homework help

    Quote Originally Posted by davellew69 View Post
    thanks for the reply, I have just done it all again and the scientific calculator is giving me my origional answer,.....
    Well, you're not "feeding it" properly then: the FULL [-b +- SQRT(b^2 - 4ac)] has to be divided by (2ac);
    you're going: -b +-[SQRT(b^2 - 4ac)]/(2ac) ; OK?
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  5. #5
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    Re: quadratic homework help

    same answer as I get the first time
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  6. #6
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    Re: quadratic homework help

    @wilma


    just 2a

    @OP degrees mode calculator?
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  7. #7
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    Re: quadratic homework help

    I see what you've done wrong here...

    You've put 11+ on its own so you're doing 11 +- (root97 / 2)

    What you want to do is (11+- root97) / 2
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  8. #8
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    Re: quadratic homework help

    you have lost me vince
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  9. #9
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    Re: quadratic homework help

    What you did:



    What you should have done:


    The 11+ or - goes within the divide by 2 part, which you put outside of it.
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  10. #10
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    Re: quadratic homework help

    why do i do it that way?
    Last edited by davellew69; April 1st 2012 at 07:30 AM.
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  11. #11
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    Re: quadratic homework help

    lol got it...now I see why the brackets are used that way on a scientific calculator, thanks so much for your help..top fella, many thanks

    Dave
    ( I may get got at this one day lol)
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  12. #12
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    Re: quadratic homework help

    If you have a scientific calculator:

    fraction button -> 11 +- square root 97 -> down button -> 2

    Natural display calculators mean you don't need the brackets on the calculator.

    If you need more help just PM me here and it'll give me an email.
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  13. #13
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    Re: quadratic homework help

    C'mon Dave...relax...:
    4 + 10/2 = 9
    (4 + 10)/2 = 7

    Get it?
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