Results 1 to 3 of 3

Math Help - solving a equation

  1. #1
    Junior Member
    Joined
    Nov 2011
    From
    Chelmsford, Essex, UK
    Posts
    67

    solving a equation

    hi would I solve equations such as

    y=-3x+2

    and

    y=2x^2-7x-4

    by factorising or using the quad formula, as I need to find where the above intersect on a graph.

    Many thanks

    Dave
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Mar 2012
    From
    Sheffield England
    Posts
    440
    Thanks
    76

    Re: solving a equation

    Quote Originally Posted by davellew69 View Post
    hi would I solve equations such as

    y=-3x+2

    and

    y=2x^2-7x-4

    by factorising or using the quad formula, as I need to find where the above intersect on a graph.

    Many thanks

    Dave
    At intersection 2x^2-7x-4= -3x+2 So 2x^2 -4x -6=0 Divide both sides by 2 giving x^2-2x-3=0 Now factorize and get two values for x.
    Sub these back into y= -3x+2 to get the corresponding values of y.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Oct 2011
    Posts
    37

    Re: solving a equation

    This is just a simple simultaneous equation. There will of course be 2 intersection points. y=2x^2-7x-4 is a parabola and y=-3x+2 will intersect it at 2 points.

    as y=y then 2x^2-7x-4=-3x+2

    Therefore, 2x^2-7x-4=-3x+2=2x^2-4x-6

    \frac{2x^2-4x-6}{2} = x^2-2x-3

    This is a quadratic, so factorise this equation and it will give you two points for x. Put these back into the equation, and you will retrive the values for y.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Solving an equation for x
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: July 27th 2010, 12:00 PM
  2. I need help solving an equation
    Posted in the Calculus Forum
    Replies: 5
    Last Post: April 4th 2010, 07:16 PM
  3. solving this equation.
    Posted in the Algebra Forum
    Replies: 6
    Last Post: September 9th 2008, 04:41 AM
  4. solving diff equation w/ bournoulli's equation
    Posted in the Calculus Forum
    Replies: 2
    Last Post: February 14th 2008, 07:06 PM
  5. solving the equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: February 3rd 2007, 03:19 PM

Search Tags


/mathhelpforum @mathhelpforum