1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Linear Algebra Help?

  1. Jun 18, 2013 #1
    1. The problem statement, all variables and given/known data
    Find a system of two equations in two variables, x and y, that has the solution set given by the parametric representation x=t and y=3t-4, where t is any real number.

    2. Relevant equations
    x=t and y=3t-4, where t is any real number

    3. The attempt at a solution
    y=3x-4 which means that x=(y+4)*1/3. But that is still only one equation and I can't figure out what the other one is. If there are two equations with two unknowns, couldn't the solutions be precise numbers? Since the solution given is parametric, I think there is only one equation in two variables. However, this does not satisfy the question's requirements. What is going on?
  2. jcsd
  3. Jun 18, 2013 #2


    User Avatar
    Science Advisor
    Homework Helper

    I agree with you. It's probably just a mistake in the problem. If you want a second equation you could always suggest something like x=x or something else redundant. But that's pretty pointless.
  4. Jun 18, 2013 #3
    OK thanks for confirming my thought.
  5. Jun 19, 2013 #4


    User Avatar
    Science Advisor

    Two independent equations in x and y will necessarily have a unique solution, not an infinite set of equations as you are given. Yes, x and y must satisfy y= 3x- 4 which I would write as 3x- y= 4. A second equation must be a multiple of that, say, 9x- 3y= 12.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted