Results 1 to 2 of 2

Math Help - Find numbers A & B

  1. #1
    Junior Member
    Joined
    Jun 2008
    From
    Sanger, CA
    Posts
    58

    Post Find numbers A & B

    Find numbers A & B such that for all x, x + 2 = A(x - 3) + B(x + 1)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Apr 2005
    Posts
    1,631
    Quote Originally Posted by katchat64 View Post
    Find numbers A & B such that for all x, x + 2 = A(x - 3) + B(x + 1)
    x +2 = A(x -3) +B(x +1) ------(i)
    x +2 = Ax -3A +Bx +B
    x +2 = (A +B)x +(-3A +B) ------(ii)

    For (ii) to be true,

    a)the coefficient of x in the LHS must be equal to the coefficient of x in the RHS.
    Or, 1 = A +B -----------(iii)

    b) and the constants on both sides of the equation (ii) must also be equal.
    Or,
    2 = -3A +B ------------(iv)

    Now solve (iii) and (iv) simultaneously to find A and B.
    You'd get
    A = -1/4
    B = 5/4
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. find all numbers x
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: January 24th 2010, 01:51 PM
  2. Replies: 3
    Last Post: September 23rd 2009, 12:04 PM
  3. Replies: 2
    Last Post: April 30th 2009, 06:28 AM
  4. Find the Numbers
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: December 7th 2008, 09:06 AM
  5. Find All Numbers x
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: October 4th 2008, 09:07 AM

Search Tags


/mathhelpforum @mathhelpforum