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Problems To Quadratic Equations, HELP

  • 27-09-2005 04:54PM
    #1
    Registered Users, Registered Users 2 Posts: 2,386 ✭✭✭


    Hello
    Have done every single sum given regarding these, but this one for some reason is giving me problems:(

    please work out this problem and post to show the workings, i basically want to know the equation

    One Whole Number is 3 larger than twice another whole number. The sum of the squares of these two numbers is 194. Find the two numbers.

    THANKS, the thing i dont get really is the sum of the squares


Comments

  • Registered Users, Registered Users 2 Posts: 16,239 ✭✭✭✭Pherekydes


    Let x,y be the two numbers.

    y = 2*x + 5;

    x^2 + y^2 = 194;

    Sub for y in (2):

    x^2 + (2*x + 3)^2 = 194;

    x^2 + 4*x^2 + 12*x + 9 = 194;

    5*x^2 + 12*x - 185 = 0;

    The solns are x =(5, -37/5)

    We want a whole number soln, so x = 5 is the one we want.

    Thus y = 13.


  • Registered Users, Registered Users 2 Posts: 2,386 ✭✭✭shortys94


    aorry but whats ^


  • Registered Users, Registered Users 2 Posts: 1,285 ✭✭✭eoinf


    x^2 = x squared (x to the power of two) or x*x


  • Registered Users, Registered Users 2 Posts: 1,501 ✭✭✭Delphi91


    Slow coach wrote:
    Let x,y be the two numbers.

    y = 2*x + 5;

    ...

    That should be y = 2*x + 3!


  • Registered Users, Registered Users 2 Posts: 16,239 ✭✭✭✭Pherekydes


    Delphi91 wrote:
    That should be y = 2*x + 3!

    Yeah, spotted that typo. :eek:


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