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September 18, 2014

September 18, 2014

Posted by **Jack** on Wednesday, June 20, 2007 at 2:53pm.

I'm currently working on solving algebraic equations with two variables (Example: 3x+4y=9). The computer lesson has taught me nothing but to solve the equation by trial and error -- selecting the proper ordered pair from a multiple choice list after plugging it in to see if it's correct. So, what happens when I don't have a convenient little list of ordered pairs to plug in? Is there a way to solve it from scratch like a one-variable equation?

There is a way to solve this problem from scratch.

You first find a value for either X or Y and then plug that instead of X or Y and solve for the other one.

3X + 4Y = 9

3X = 9 - 4Y

X = (9-4Y)/3

Now plug that instead of X to make it a one variable equation.

3[(9-4Y)/3) + 4Y = 9

That should result as Y=1

Than, plug 1 instead of Y to get X.

3X + 4(1)=9

that should result as X = 5/3

Than, plug the number for both X and Y.

3(5/3) + 4(1)=9

9=9

Hope it helps.

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