Results 1 to 9 of 9

Thread: Math Equation

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    One Hundred Chimneys Recognized Member Tavrobel's Avatar
    Join Date
    Jan 2006
    Location
    Conjunction Junction
    Posts
    10,455
    Articles
    102
    Contributions
    • Former Site Staff

    Default

    Quote Originally Posted by Depression Moon View Post
    (3x - 8) = 4 + 2(x - 4)1/2 + x - 4
    This is where you squared right? I understand where you got that first 4, but i'm unsure about the 2 and the x-4.

    In comparison to the example problem at this step. I don't know how to use subscripts like you so I apologize.

    2x-1 = x-5+6 the square root of x-5 + 9


    Just to mention in the hinto I'm shown there is no paretheses around the square root of x-5 is it still assumed to multiply?
    < sup >exponent< / sup > except, without the spaces.

    So, let's break up (2 + (x - 4)<sup>1/2</sup>)<sup>2</sup>
    (2 + (x - 4)<sup>1/2</sup>) * (2 + (x - 4)<sup>1/2</sup>)

    Also, I screwed up, since the coefficient should be 4, not 2.

    FOIL:
    First terms
    (2 + (x - 4)<sup>1/2</sup>) * (2 + (x - 4)<sup>1/2</sup>)
    Outer terms
    (2 + (x - 4)<sup>1/2</sup>) * (2 + (x - 4)<sup>1/2</sup>)
    Inner terms
    (2 + (x - 4)<sup>1/2</sup>) * (2 + (x - 4)<sup>1/2</sup>)
    Last terms
    (2 + (x - 4)<sup>1/2</sup>) * (2 + (x - 4)<sup>1/2</sup>)

    2*2 + 2*(x - 4)<sup>1/2</sup> + 2*(x - 4)<sup>1/2</sup> + (x - 4)
    4 + 4(x - 4)<sup>1/2</sup> + x - 4
    4(x - 4)<sup>1/2</sup> + x
    3x - 8 = 4(x - 4)<sup>1/2</sup> + x
    2x - 8 = 4(x - 4)<sup>1/2</sup>
    x/2 - 2 = (x - 4)<sup>1/2</sup>

    Square both sides:
    (x/2 - 2)<sup>2</sup> = ((x - 4)<sup>1/2</sup>)<sup>2</sup>
    x<sup>2</sup>/4 - 2x + 4 = x - 4
    x<sup>2</sup>/4 - 3x + 8 = 0

    Multiply everything by 4 to get rid of the denominator:
    x<sup>2</sup> - 12x + 32 = 0

    Different answer. (x - 8)(x - 4) = 0; therefore, x = 8, 4.

    %%
    (2x - 1) = (x - 5) + 6(x - 5)<sup>1/2</sup> + 9?
    Last edited by Tavrobel; 02-04-2010 at 11:46 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •