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: How do i solve the system of equation

  1. Jun 22, 2010 #1
    1. The problem statement, all variables and given/known data
    I need to find a,b,c from

    2. Relevant equations

    3. The attempt at a solution

    The furthest Ive gone is

  2. jcsd
  3. Jun 22, 2010 #2
    im not sure what you have done?
    you can start by subtracting the first equation from third equation, then you will have the value of c
    after that you can use this value in the second equation to get either a in terms of b or b in terms of a, after that you can easily substitute again in the first or third equation to get your answer..
  4. Jun 22, 2010 #3


    Staff: Mentor

    You lost your variable! 3a = .3 ==> a = .1
    Now substitute for a in two other equations to get two equations in b and c, which you can solve for those variables.
  5. Jun 22, 2010 #4


    User Avatar
    Science Advisor

    What you did the first time was add the second and third equations, eliminating both b and c at the same time to get a= .1.

    Now, you can, as Mark44 suggests, set a= .1 in those three equations reducing to two equations for b and c. (Only two equations because a= .1 makes the second and third equations, that you used to get a, the same.)

    Or you can do as Thebigstar25 suggests- subtract the first equation from the third equation. That eliminates both a and b at the same time, allowing you to solve for c.

    Once you have found a and c, put those values into any of the three equations and solve for b.
  6. Jun 22, 2010 #5
    Ok thanks for the fast reply because it really helped !
  7. Jun 22, 2010 #6
    I do not know if you have learned about Cramer's Rule, but you might want to look into this, it will make this problem very simple to solve.
    Last edited: Jun 22, 2010
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook