Results 1 to 4 of 4

Math Help - Please verify

  1. #1
    Member
    Joined
    Dec 2009
    Posts
    122

    Please verify

    I would appreciate verification on the following: 1) Completely factor the expression: a^2 + 4b -ab - 4a (I have (a+b)(a-4) ) 2) completely factor r^2-2r+1 (I have r(r-2)+1 ) Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member bigwave's Avatar
    Joined
    Nov 2009
    From
    honolulu
    Posts
    580
    its easy to check these
    just expand the brackets

    (a+b)(a-4) = a^2 - 4a + ba -4b

    which is not your original equation

    the second one should be (r-1)^2
    Last edited by bigwave; January 14th 2010 at 10:13 PM. Reason: spelling
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Master Of Puppets
    pickslides's Avatar
    Joined
    Sep 2008
    From
    Melbourne
    Posts
    5,236
    Thanks
    28
    Quote Originally Posted by jay1 View Post
    Completely factor the expression: a^2 + 4b -ab - 4a
    a^2 + 4b -ab - 4a

    Grouping

    a^2 -ab -4a+ 4b

    (a^2 -ab) -(4a- 4b)

    Find a common factor in each group

    a(a -b) -4(a- b)

    Can you see the common factor?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member nikhil's Avatar
    Joined
    Jun 2008
    Posts
    292

    keep in mind

    an equation in the form ax^2+bx+c=0 is called a quadratic equation. it can always be written as product of two factors.

    1) a^2+4b-ab-4a
    =a^2-ab+4b-4a
    =a(a-b)+4(b-a)
    =(a-b)(a-4) [there are two factors]
    2)r^2-2r+1
    =r^2-r-r+1
    =r(r-1)-(r-1)
    =(r-1)(r-1) (again two factors though equal)
    =(r-1)^2
    so before writing r(r-2)+1 remember quadratic equations can be written as product of two factors
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Verify that x = 1 => fg(x) = gf(x)
    Posted in the Algebra Forum
    Replies: 8
    Last Post: June 27th 2010, 07:05 PM
  2. verify
    Posted in the Algebra Forum
    Replies: 5
    Last Post: January 25th 2010, 05:33 PM
  3. verify uh...
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: September 30th 2009, 11:37 PM
  4. Verify
    Posted in the Advanced Algebra Forum
    Replies: 2
    Last Post: September 7th 2008, 07:08 PM
  5. verify this one
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: October 6th 2005, 06:26 AM

Search Tags


/mathhelpforum @mathhelpforum