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Basic algebra question

  1. Jul 17, 2006 #1
    basic algebra question plz help :(

    when combining the two equations

    Vb-0.5FAC = 10
    Hb -0.866FAC = -2

    It brings the answer 1.732Vb - Hb = 19.32


    can someone plx explain to me how this answer came about
     
  2. jcsd
  3. Jul 17, 2006 #2

    Office_Shredder

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    You have Vb, Hb, and FAC as variables with only two equations?

    Of course you're not going to solve it. Do these variable stand for something significant? Perhaps there is a third equation that you're missing
     
  4. Jul 17, 2006 #3
    They substituted FAC from the first equation into the second one. Now try to find this answer yourself.
     
  5. Jul 17, 2006 #4
    the answer i got myself was
    1.732Vb - Hb = 12

    i got no idea how they got 19.32
     
  6. Jul 17, 2006 #5
    did you came up with FAC = -20 + 2Vb ?
     
  7. Jul 17, 2006 #6
    yes that is correct


    there is actually a third equation that when combined with the first two equations gives all the answers

    the third equation is
    2Vb - 3Hb = -26


    the final answers are

    Vb = 26.2
    Hb = 26.1
    FAC = 32.4



    The problem i have is that i dont understand how the first two equations combined together gave the answer of 1.732Vb - Hb = 19.32

    if you could write down the step by step procedure on how this answer came about it would be greatly appreciated.
     
  8. Jul 17, 2006 #7
    i won't write down all my steps because it's not allowed. Here is how you get to the equation that leads to 1,732Vb - Hb = 19,32:

    From equation 1 it follows that:

    [tex] FAC = \frac {(10-Vb)} {-0,5} \ = -2 (10-Vb) = -20 + 2Vb [/tex]

    This can be put in the second equation:

    [tex]Hb -0.866(-20 + 2Vb) = -2 [/tex]

    This will deliver your asked formula when properly worked out.
     
    Last edited: Jul 17, 2006
  9. Jul 17, 2006 #8
    thank you so much

    i swear to god if i had a credit card i would pay you 5 dollers
     
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