Results 1 to 3 of 3

Math Help - factorise, hard

  1. #1
    Super Member
    Joined
    Oct 2008
    From
    Bristol, England
    Posts
    897

    factorise, hard

    hi i need to know how to factorise this:

    factorise, hard-factorise.jpg

    i know if it was 2x^2 - 121 it would = (x+11) (x-11)
    so for this one would it be (2x +11) (2x-11) ???

    if not could you please tell me where im going wrong!

    Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Amer's Avatar
    Joined
    May 2009
    From
    Jordan
    Posts
    1,093
    Quote Originally Posted by andyboy179 View Post
    hi i need to know how to factorise this:

    Click image for larger version. 

Name:	factorise.jpg 
Views:	26 
Size:	6.5 KB 
ID:	20407

    i know if it was 2x^2 - 121 it would = (x+11) (x-11)
    so for this one would it be (2x +11) (2x-11) ???

    if not could you please tell me where im going wrong!

    Thanks!
    if it is x^2 - 121 = (x -11)(x + 11 )
    but 2x^2 - 121 is not equal to (x- 11)(x+11)

    ur solution for the question is rite 4x^2 - 121 = (2x - 11)(2x +11)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,569
    Thanks
    1410
    In general, [tex]a^2- b^2= (a- b)(a+ b)/[tex]

    Actually, 2x^2- 121= (\sqrt{2}x)^2- 11^2= (\sqrt{2}x- 11)(\sqrt{2}x+ 11), not (x- 11)(x+ 11). I presume that was a mis-type.

    4x^2= (2x)^2 so, yes, 4x^2- 121= (2x- 11)(2x+ 11).
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Factorise 5ct-5c+6-6t
    Posted in the Algebra Forum
    Replies: 3
    Last Post: February 24th 2011, 02:14 AM
  2. [SOLVED] Factorise ac-3+3x-a
    Posted in the Algebra Forum
    Replies: 3
    Last Post: February 23rd 2011, 05:58 AM
  3. hard factorise
    Posted in the Algebra Forum
    Replies: 1
    Last Post: November 23rd 2010, 10:00 AM
  4. factorise
    Posted in the Algebra Forum
    Replies: 5
    Last Post: October 8th 2010, 06:32 AM
  5. Factorise
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 10th 2008, 12:04 AM

Search Tags


/mathhelpforum @mathhelpforum