Comments on: What are the steps of the addition and substitution methods? http://www.mathstudenthelp.info/addition/what-are-the-steps-of-the-addition-and-substitution-methods Let us help you add it up! Sun, 12 Feb 2012 09:03:19 +0000 http://wordpress.org/?v=2.7 hourly 1 By: hayharbr http://www.mathstudenthelp.info/addition/what-are-the-steps-of-the-addition-and-substitution-methods/comment-page-1#comment-7075 hayharbr Wed, 10 Feb 2010 17:48:59 +0000 http://www.mathstudenthelp.info/addition/what-are-the-steps-of-the-addition-and-substitution-methods#comment-7075 Most always, you can do either one. Substitution is often easier when one variable is all by itself, or easy to get all by itself, as in" 2x + 3y = 8 x = y - 1 You'd just substitute (y - 1) for the x in equation 1 getting 2(y - 1) + 3y = 9 2y - 2 + 3y = 8 5y - 2 = 8 5y = 10 y = 2 then plug that in to get x. But if it's not easy to get a variable by itself, addition is usually easier. As in 2x + 3y = 8 4x + 7y = 18 You would multiply row 1 by -2 then add it to row 2 which will eliminate the x: -4x -6y = -16 4x + 7y = 18 --------------- 1y = 2 so again y = 2; plug in to get x That's basically it<br><b>References : </b><br> Most always, you can do either one. Substitution is often easier when one variable is all by itself, or easy to get all by itself, as in"
2x + 3y = 8
x = y - 1

You’d just substitute (y - 1) for the x in equation 1 getting 2(y - 1) + 3y = 9
2y - 2 + 3y = 8
5y - 2 = 8
5y = 10
y = 2 then plug that in to get x.

But if it’s not easy to get a variable by itself, addition is usually easier. As in

2x + 3y = 8
4x + 7y = 18

You would multiply row 1 by -2 then add it to row 2 which will eliminate the x:

-4x -6y = -16
4x + 7y = 18
—————
1y = 2

so again y = 2; plug in to get x

That’s basically it
References :

]]> By: Emily http://www.mathstudenthelp.info/addition/what-are-the-steps-of-the-addition-and-substitution-methods/comment-page-1#comment-7074 Emily Wed, 10 Feb 2010 17:09:59 +0000 http://www.mathstudenthelp.info/addition/what-are-the-steps-of-the-addition-and-substitution-methods#comment-7074 Usually when you have a large equation, you are to use "PEMDAS" which stands for Parenthesis-Exponents-Multiply-Divide-Add-Subtract. This is the order in which the problem should be solved, starting with numbers in parenthesis, then numbers with exponents and so on. Hope this is what you were asking for. ; )<br><b>References : </b><br>Math Class. Usually when you have a large equation, you are to use "PEMDAS" which stands for Parenthesis-Exponents-Multiply-Divide-Add-Subtract. This is the order in which the problem should be solved, starting with numbers in parenthesis, then numbers with exponents and so on.

Hope this is what you were asking for. ; )
References :
Math Class.

]]> By: ??????? ? JON ? ??????? http://www.mathstudenthelp.info/addition/what-are-the-steps-of-the-addition-and-substitution-methods/comment-page-1#comment-7073 ??????? ? JON ? ??????? Wed, 10 Feb 2010 16:25:59 +0000 http://www.mathstudenthelp.info/addition/what-are-the-steps-of-the-addition-and-substitution-methods#comment-7073 it really just depends on what they ask for, and what is easiest. If they don't specify one or the other, just do it one way, and if that's too hard, try it the other way<br><b>References : </b><br> it really just depends on what they ask for, and what is easiest. If they don’t specify one or the other, just do it one way, and if that’s too hard, try it the other way
References :

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