Help With Precalc Algebra Hw Please

Discussion in 'General' started by Boson-H, May 22, 2013.

  1. i might ask a few in this thread, i'm so confused for some reason....question one, in this example
    LCD is x(x+2), you see the 2nd like where in blue it says expand?  i realize in the left hand side of the equation they cross multiplied, but what in the hell happened to the x(x+2)?  They distributed it on the RHS so wtf.  thats the only thing stumping me right now.

  2. math sucks
  3. 2x(x+2) = 2x^2 +4x
  4. Well when you multiply by the LCD it ends up looking like this before you actually multiply anything:
    [3•x•(x+2)]/x + [5•x•(x+2)]/(x+2)

    Sorry if you can't read my math typing ;p I'm at work on the mobile site and can't figure out how to post pics. Basically the book skipped a step in the procedure. They cancel the denominators of the fraction using x(x+2). Hope that helps!
  5. Its because when you are multiplying those numbers, the LCD basically takes away anything on the bottom that resembles the LCD.
    The 3/x is multiplied by x(x+2), then the product is 3(x+2), because the LCD cancels things out.
    5/x+2 is multiplied by x(x+2), and the x+2's cancel, leaving with just an x, so 5x.
    Right side just distributes since the denominator for 2x is 1.
  6. ok sweet thanks y'all...i got that one down now!
    anyone wanna help with a different one stumping me?
    1/x-1 + 1/x+2 = 5/4
    now to find LCD you multiply the denoms right?  when i do that (x-1)(x+2) using FOIL i get x^2+x-2, and then i have to multiply that by both sides of the eqution?  how do i multiply x^2+x-2 by 1/x-1 ?
  7. #7 Dryice, May 22, 2013
    Last edited by a moderator: May 22, 2013
    I have no interest in checking to see if your work is right prior,
    But multiplying x^2+x-2 by 1/x-1 all you have to do is look at x^2+x-2 as a fraction which is (x^2+x-2)/1 and multiply straight across.
    edit: grouping symbols
  8. #8 stenod, May 22, 2013
    Last edited by a moderator: May 22, 2013
  9. @stenod Microsoft Mathematics is good too. 

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