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Solving for x (this should be easy but somehow I keep messing it up!)

  1. Aug 11, 2012 #1
    I'm starting college this fall. I asked one of my professors if we had a textbook and he said that there's an online version and I should read a bit of it if I wanted to.
    On the first chapter they were talking about simple (I mean really simple algebra, this is a vector geometry class) but I got completely stumped on one of the problems.

    I got an answer but it seems to be different from the textbook answer. I tried putting in number valves for the variable in the 2 different solution but i got different solutions. I probably did this wrong s0 can someone help me solve this I don't want to be stumped on my first week of college with the engineers >.<

    It should be uploaded on this message as an attachment.

    What I Did:

    called "problem my way" attachment

    Supposed Answer: attachment called "answer"

    Attached Files:

  2. jcsd
  3. Aug 11, 2012 #2


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    Homework Helper

    You're answer is the same as the given solution. You just have to clean your expression up a bit.
    [tex]x = \frac{e}{\frac{c - a}{a + 1/b} - d} - c[/tex]
    Take the fraction in the denominator and multiply by [itex]\frac{b}{b}[/itex]
    [tex]x = \frac{e}{\frac{b(c - a)}{ba + 1} - d} - c[/tex]
    Perform the subtraction in the denominator by finding the LCD (which is ba + 1):
    [tex]x = \frac{e}{\frac{b(c - a)}{ba + 1} - \frac{d(ba + 1)}{(ba + 1)}} - c[/tex]
    [tex]x = \frac{e}{\frac{b(c - a) - d(ba + 1)}{ba + 1}} - c[/tex]
    Multiply the entire fraction by [itex]\frac{ba + 1}{ba + 1}[/itex]
    [tex]x = \frac{e(ba + 1)}{b(c - a) - d(ba + 1)} - c[/tex]

    Note to mods: I don't think I'm giving too much away here. This is not in the HW subforum and the OP did show a lot of the work.
  4. Aug 12, 2012 #3
    I find it useful to do some substitutions when solving these, you could clean up the expression given and make things a lot easier
  5. Aug 14, 2012 #4
    Oh, THANK YOU!!! I tried using substitution to check but yeah since it's so messy I probably messed up somewhere. Thank you so much!!! This problem was really starting to freak me out. Thank you, eumayang, for cleaning it up! I tried converting my answer to the book's answer but I was really confused on how to do it.
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