Results 1 to 4 of 4

Math Help - Solving system of equations algebraically?

  1. #1
    Senior Member
    Joined
    Dec 2010
    From
    CPT
    Posts
    302

    Solving system of equations algebraically?

    I am trying to solve this system of equations

    (y-1)^2=4+x

    x+y=-1

    This is what I did

    y^2-1y-1y-1y+1=4+x
    y^2-2y+1=4+x
    y^2-2y-3=x

    Then I used the quadratic formula to get x=-3

    Then plugged that in to x+y=1
    I got y=2

    Now I am confused because according to my book there are two solutions for this program I found (-3,2)

    But I am having trouble finding the other solution?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    May 2011
    Posts
    169
    x= -(1+y)
    (y-1)^2=4-(1+y)
    y^2-2y+1-4+1+y=0
    y^2-y-2=0

    You continue.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Dec 2010
    From
    CPT
    Posts
    302
    Would you have to use the quadratic formula?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member bigwave's Avatar
    Joined
    Nov 2009
    From
    honolulu
    Posts
    580

    foil

    just continuing from above

    \left(y-1\right)^2 = 4 + \left(-1-y\right)
    y^2 - y -2=0
    \left(y+1\right)\left(y-2\right)
    so
    y=-1 and y=2
    now plug into x+y=-1
    you get
    x=0 and x=-3
    this is 2 graphs intersecting each other at (-3,2) and (0,-1)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Solving a system of 4 equations
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 7th 2012, 06:31 AM
  2. Solving Quadratic Trig Equations Algebraically
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: June 7th 2011, 08:20 AM
  3. solving trigonometry equations algebraically
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: April 2nd 2010, 08:53 PM
  4. Replies: 5
    Last Post: May 14th 2009, 01:18 PM
  5. Solving the system of equations
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: March 25th 2009, 06:50 PM

Search Tags


/mathhelpforum @mathhelpforum