Results 1 to 12 of 12

Math Help - Simultaneous equation

  1. #1
    Junior Member
    Joined
    May 2011
    Posts
    37

    Simultaneous equation

    Hi guys would appreciate any help at geting to the correct answer step by step

    2y=10 + x
    y=3x + 5

    The solution should be x=0 y=5

    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78
    Quote Originally Posted by komodo View Post
    Hi guys would appreciate any help at geting to the correct answer step by step

    2y=10 + x
    y=3x + 5

    The solution should be x=0 y=5

    Thanks
    What method are you using or is it your choice?

    You can use graphing, Substitution, or Linear combinations.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    May 2011
    Posts
    37
    Quote Originally Posted by TheEmptySet View Post
    What method are you using or is it your choice?

    You can use graphing, Substitution, or Linear combinations.
    Personaly I'm using the manipulating method since I understand it better.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,406
    Thanks
    1294
    You won't get step by step solutions, but the substitution method is the most appropriate here, since you already know what y is in terms of x.

    Substituting into the first equation gives 2(3x + 5) = 10 + x. Solve for x, then back-substitute and solve for y.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    May 2011
    Posts
    37
    Quote Originally Posted by Prove It View Post
    You won't get step by step solutions, but the substitution method is the most appropriate here, since you already know what y is in terms of x.

    Substituting into the first equation gives 2(3x + 5) = 10 + x. Solve for x, then back-substitute and solve for y.
    I dont understand if I'm supposed to multiply the 3 by the bracket then I get x=15/16 which is 0.9375 and this is not the right solution.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,406
    Thanks
    1294
    Why would you multiply by 3? It's telling you to multiply by 2...
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    May 2011
    Posts
    37
    Quote Originally Posted by Prove It View Post
    Why would you multiply by 3? It's telling you to multiply by 2...
    Yeah sorry I got mixed up with something else I'm looking at.....this is what I get for x after going through the different steps:

    2(3x + 5) = 10 + x
    = 6x + 10 = 10 + x
    = 7x + 20
    x = 20/7 = 2.86

    Where am I going wrong since x is supposed to be 0 and Y=5 ????

    Thanks
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,845
    Thanks
    320
    Awards
    1
    Quote Originally Posted by komodo View Post
    Yeah sorry I got mixed up with something else I'm looking at.....this is what I get for x after going through the different steps:

    2(3x + 5) = 10 + x
    = 6x + 10 = 10 + x
    6x + 10 = 10 + x

    Add -10 to both sides:
    6x + 10 - 10 = 10 + x - 10

    6x = x

    Go from there.

    -Dan
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Junior Member
    Joined
    May 2011
    Posts
    37
    Quote Originally Posted by topsquark View Post
    6x + 10 = 10 + x

    Add -10 to both sides:
    6x + 10 - 10 = 10 + x - 10

    6x = x

    Go from there.

    -Dan
    Which clearly makes x = 0 and y = 5 ....Thanks Dan

    I was under the impression that one must gather similar terms from the examples I've been looking through seems thats not the case here.
    Follow Math Help Forum on Facebook and Google+

  10. #10
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,845
    Thanks
    320
    Awards
    1
    Quote Originally Posted by komodo View Post
    Which clearly makes x = 0 and y = 5 ....Thanks Dan

    I was under the impression that one must gather similar terms from the examples I've been looking through seems thats not the case here.
    Well, if you want to look at it that way....
    6x + 10 = 10 + x

    6x + 10 - x - 10 = 0

    5x = 0

    -Dan
    Follow Math Help Forum on Facebook and Google+

  11. #11
    Super Member
    Joined
    Nov 2007
    From
    Trumbull Ct
    Posts
    904
    Thanks
    27
    Dear komoda,
    Did you rewrite 2y =10+x into y=1/2x + 5 Then what do you know about the solution without doing any calcs
    Follow Math Help Forum on Facebook and Google+

  12. #12
    Junior Member
    Joined
    May 2011
    Posts
    37
    Yeah I see where I messed up....thanks guys
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Simultaneous equation
    Posted in the Algebra Forum
    Replies: 19
    Last Post: September 30th 2011, 09:11 AM
  2. Simultaneous equation with cos or sin
    Posted in the Algebra Forum
    Replies: 4
    Last Post: September 20th 2009, 12:48 PM
  3. simultaneous equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: September 20th 2009, 05:52 AM
  4. Simultaneous equation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: September 15th 2009, 04:07 AM
  5. Simultaneous Equation Help Please!
    Posted in the Algebra Forum
    Replies: 3
    Last Post: April 15th 2008, 11:22 AM

Search Tags


/mathhelpforum @mathhelpforum