Results 1 to 2 of 2

Math Help - Help With Simultaneous Equations

  1. #1
    Newbie
    Joined
    Jul 2012
    From
    Australia
    Posts
    1

    Help With Simultaneous Equations

    So i'm having trouble with simultaneous equations, the equations are:

    y^2 + x^2 = 150^2
    3y + 2x = 180

    Looks quite simple but i'm not sure where to get started mainly because of the '150^2'.
    Please help.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member BAdhi's Avatar
    Joined
    Oct 2010
    From
    Gampaha, Sri Lanka
    Posts
    252
    Thanks
    6

    Re: Help With Simultaneous Equations

    you can isolate y (or x) from the second equation, so that

    y=60-\frac{2x}{3}

    then substitute it to the first equation,

    \begin{align*}\left(60-\frac{2x}{3}\right)^2+x^2 &=150^2\\60^2-\frac{2\times 60\times 2x}{3}+\frac{4x^2}{9}+x^2&=150^2\\\frac{4x^2}{9}+x  ^2-80x+(60-150)(60+150)&=0\\13x^2-720x+9\times (-90)\times 210&=0\\13x^2-720x-170100&=0 \end{align*}

    this is a quadric equation, hope you can solve it
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. simultaneous equations
    Posted in the Algebra Forum
    Replies: 8
    Last Post: January 8th 2012, 11:21 AM
  2. Simultaneous Equations 4 variables, 4 equations
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: December 7th 2011, 05:06 PM
  3. Simultaneous Equations
    Posted in the Algebra Forum
    Replies: 6
    Last Post: May 9th 2009, 04:35 AM
  4. Replies: 3
    Last Post: February 27th 2009, 08:05 PM
  5. simultaneous equations
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: January 18th 2008, 05:38 PM

Search Tags


/mathhelpforum @mathhelpforum