Quadratic equations!

Discussion in 'Bulletin Board ARCHIVE' started by Guest, Sep 18, 2005.

  1. Gue

    Guest Guest

    can anybody show me how to find x in this quadratic eqaution:
    2xsquared+17x+8=0??? :S

    Cumon ne maths genius's out there, nows your chance to shine!!!
     
  2. Gue

    Guest Guest

    (2x+1)(x+8)=0

    Therefore either (2x+1)=0,
    or (x+8)=0
     
  3. Tomi

    Tomi Well-Known Member

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    For all quadratic equations (axsquared + bx + c = 0) you can find the solution with the following formula:

    [​IMG]

    In this case, a=2; b=17; c=8

    --> x = -1/2 OR x = -8
     
  4. Gue

    Guest Guest

    RE: (2x+1)(x+8)=0

    how did ya get that??
     
  5. Tomi

    Tomi Well-Known Member

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    ICU Tyke's solution is just as good of course, in this case it's probably even better. :)
     
  6. Gue

    Guest Guest

    How did he get that though, cos i've got t show my workin! :S
     
  7. Tomi

    Tomi Well-Known Member

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    You have to divide it to two (or more) first degree terms, and find the x for both of them.
    If I knew the mathematical terminology in English any better then I'd be able to help, but now someone else has to explain this to you. :S
    Does the formula that I suggested look any familiar to you? Perhaps you could use that instead...
     
  8. Tomi

    Tomi Well-Known Member

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    RE: (2x+1)(x+8)=0

    2xsquared+17x+8 = (2x+1)(x+8)
     
  9. EastStander

    EastStander Active Member

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    What happened to the 17?
     
  10. Journo Tyke

    Journo Tyke Well-Known Member

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    RE: What happened to the 17?

    2x * 8 = 16x
    x * 1 = x

    16x + x = 17x
     
  11. Tomi

    Tomi Well-Known Member

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    RE: What happened to the 17?

    (2x+1)(x+8) = 2x*x + 2x*8 + 1*x + 1*8
    = 2xsquared + 17x + 8

    :)
     
  12. Gue

    Guest Guest

    RE: What happened to the 17?

    Rite, am getting a little lost here, can someone, put it step by step on how to calculate this equation??
     
  13. Journo Tyke

    Journo Tyke Well-Known Member

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    RE: What happened to the 17?

    Tomi just did mate, that's how to do it...
     
  14. Gue

    Guest Guest

    Sorry, I went off to do something else without explaining it....

    The quadratic equation can be shown in two forms

    ax^2+bx+c=0 or (px+q)(rx+s)=0

    a,b,c,p,q,r and s are ordinary numbers and ^2 means squared (or "to the power of 2")

    p multiplied by r makes a (in the example shown this is 2x1=2 or 1x2=2 so a and b are 1 and 2)

    q multiplied by s makes c (this could be either 1x8=8 or 2x4=8)

    p multiplied by s plus q multiplied by r equals b (this can only work if q times s is 1x8, if q times s is 2x4, then b would equal 10

    Hope that helps, and sorry if it's a bit late!
     
  15. pau

    paul.d Well-Known Member

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    (2x+1)(x+8)=0,

    2x*(x+8)+1(x+8)=0

    2x^2+16x+1x+8=0

    2x^2+17x+8=0

    write it down in reverse for a solution
     
  16. Gue

    Guest Guest

    thar an enigma, thee, Tomi.....

    Tha's obviously got some brains, and yet art on all Europe tha chose Barnsley ter suppooart........fookin ell
     

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