Results 1 to 2 of 2

Math Help - Finding a constant to make a perfect square trinomial

  1. #1
    Newbie
    Joined
    Sep 2009
    Posts
    4

    Finding a constant to make a perfect square trinomial

    find a constant to add to the binomial so that it becomes a perfect square trinomial.

    x^2-15x
    Follow Math Help Forum on Facebook and Google+

  2. #2
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Quote Originally Posted by geryuu View Post
    find a constant to add to the binomial so that it becomes a perfect square trinomial.

    x^2-15x
    Divide the coefficient of the linear term by 2 (ie divide b by 2)

    (x+7.5)^2 + k = x^2 - 15x + 0

    k = -(7.5^2)

    ---------------------------------------------------------------------

    More generally for ax^2+bx = x^2 + \frac{b}{a}x
    (we can divide by a because it must be non-zero)

    (x+\frac{b}{2a})^2 - \frac{b^2}{4a^2}

    That second term in the fraction is the constant
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding a perfect square
    Posted in the Number Theory Forum
    Replies: 3
    Last Post: June 19th 2011, 01:09 PM
  2. perfect square trinomial/square of binomial
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 3rd 2011, 05:02 PM
  3. Replies: 1
    Last Post: July 21st 2010, 03:24 PM
  4. Make a perfect square
    Posted in the Algebra Forum
    Replies: 3
    Last Post: November 22nd 2009, 09:37 AM
  5. Perfect Square Trinomial
    Posted in the Algebra Forum
    Replies: 5
    Last Post: September 30th 2008, 05:40 AM

Search Tags


/mathhelpforum @mathhelpforum