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Homework Help: Help with maths question pls

  1. Sep 24, 2005 #1
    ok this is the question:

    f(x) = 6x2 + 12x + c where C is a constant.
    a) Given f(x) =0 has equal roots, find the value of C.

    so this what i did for this part:

    b2- 4ac = 0 (formula for discriminant)
    122-4(6xC) =0
    144-24c=0
    6-C=0
    c=6 (is that right?)

    Now for the next part:
    b) Hence, solve f(x) = 0

    6x2+12x+6=0
    (x=1)(6x+6)=0
    x=-1 x= -6/6 = -1

    I wasn't really sure what i was doing but i tried to work it out and this is what i did but i'm not sure if it's right. (i don't think it is!) Can somebody help please!
     
  2. jcsd
  3. Sep 24, 2005 #2

    Päällikkö

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    Homework Helper

    a) Correct.
    b) I would've used the quadratic formula. It's correct, though.
     
  4. Sep 24, 2005 #3
    really? wow i was convinced it was wrong, thanks!
     
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