Results 1 to 3 of 3

Math Help - Question about where the (-1)! Where did it go??

  1. #1
    Junior Member
    Joined
    Feb 2008
    Posts
    71

    Question about where the (-1)! Where did it go??

    Okay so I've been sitting with this for a while and I need some help.

    36a^2-12a+1 / 1-36a

    = (simplified)

    (6a-1)(6a-1) / (1+6a)(1-6a)

    = (simplified again)

    (6a-1)(6a-1) / (-1) * (6a + 1)(6a - 1)

    = (ye again)

    - (6a - 1) / (6a + 1)

    ^ see that little minus over there? It's not supposed to be there and I dont understand where it has gone to. Could someone explain why the answer is not negative ALL THE TIME when I use the (-1) * xxxx method?

    Also now I see that the answer is supposed to be the other way = (1-6a) / 1+6a).. what says that I can't do as I first did? Somehow it does not seem wrong to me.. please someone explain this to me!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by Hanga View Post
    Okay so I've been sitting with this for a while and I need some help.

    36a^2-12a+1 / 1-36a

    = (simplified)

    (6a-1)(6a-1) / (1+6a)(1-6a)

    = (simplified again)

    (6a-1)(6a-1) / (-1) * (6a + 1)(6a - 1)

    = (ye again)

    - (6a - 1) / (6a + 1) Mr F says: This is correct. And if you take the minus back in to the top you get (-6a + 1)/(6a + 1) = (1 - 6a)/(6a + 1). All these answers are equivalent and it's a matter of choice which one is used. And obviously your book makes a choice in what it gives as its answer.

    ^ see that little minus over there? It's not supposed to be there and I dont understand where it has gone to. Could someone explain why the answer is not negative ALL THE TIME when I use the (-1) * xxxx method?

    Also now I see that the answer is supposed to be the other way = (1-6a) / 1+6a).. what says that I can't do as I first did? Somehow it does not seem wrong to me.. please someone explain this to me!
    ..
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Feb 2008
    Posts
    71
    Quote Originally Posted by mr fantastic View Post
    ..

    Thanks!

    Also... I dont even need the (-1) lol... just realized this. SILLY ME!
    Thanks though, if I understand you right I can choose to do this either cases.
    Follow Math Help Forum on Facebook and Google+

Search Tags


/mathhelpforum @mathhelpforum