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Quadratic equation without numbers?

  1. Jan 18, 2009 #1
    Quadratic equation without numbers??

    How would one go about solving an equation such as B2X2+2ABCX-ABC2 for the value of x that equals zero?

    All of the letters are constants except for X, so would this be a quadratic equation problem.?

    The solution in the book is somehow


    x=(AC/B){[tex]\sqrt{1+(B/A)}[/tex])-1}


    that -1 on the end is not the the negative 1 power, but -1
     
  2. jcsd
  3. Jan 18, 2009 #2

    Dick

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    Re: Quadratic equation without numbers??

    Yes. It's just a quadratic equation. Take the quadratic formula and put 'a'=B^2, 'b'=2ABC and 'c'=-ABC^2. Then simplify.
     
  4. Jan 18, 2009 #3
    Re: Quadratic equation without numbers??

    ok thanks dick,
    I did that before but simplifying it I could never get down to an answer that looked the same. Seemed like it would be some hardcore manipulation to get it to be that.
     
  5. Jan 18, 2009 #4
    Re: Quadratic equation without numbers??

    With the answer in front of me, I was able to do it in one step. Feel free to post your work if you continue having difficulty.
     
  6. Jan 18, 2009 #5
    Re: Quadratic equation without numbers??

    dasch...

    Are you a savant? just kidding bud, but seriously you can simplify that just like that? I honestly have used 3 maybe 4 pieces of computer paper, and its just not working out for me. Do you have an aim or something that I could communicate with you with that i could get a step through of this? Or maybe just using pm's here or whatever.
     
  7. Jan 18, 2009 #6

    Dick

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    Re: Quadratic equation without numbers??

    You would make it a lot easier for people to help you if you would post what you got and how you are trying to simplify it. It's not THAT hard.
     
  8. Jan 18, 2009 #7
    Re: Quadratic equation without numbers??

    sorry,
    That approach does seem alot better, just hard to write out the long strings of numbers sometimes on this site. And as to the being hard thing, I am only a high schol student, most of you are college grads and teachers/professors, so it might seem simple to many of you, but imagine the first time you ever did it, most likely different. Anyway,


    After quadratic equation i got this.

    (-AC +/- [tex]\sqrt{(AC)^2-(B)(-AC^2}[/tex]) all divided by B


    I took the 4 inside the square root and the 2^2 outside of the root as a 2, then the 2 in from tof -AC and the 2 on the denominator all cancelled out.

    Now where to???
     
  9. Jan 18, 2009 #8

    Dick

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    Re: Quadratic equation without numbers??

    You are already almost done. The square root is sqrt((AC)^2+(AC)^2*B/A), right? I just pulled (AC)^2 out of both terms. Now factor AC out of the square root.
     
  10. Jan 18, 2009 #9
    Re: Quadratic equation without numbers??

    woooooow...

    I really cannot believe I looked at this for this long and never saw that. Thank you very much, I dont know why i wasn't getting that, but now i see it, and finally got it!
     
  11. Jan 18, 2009 #10

    Dick

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    Re: Quadratic equation without numbers??

    See how much posting your work helps? Good job.
     
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