SOLUTION: When solving a system of equations, how do I know what numbers to put in place of x and y? An example is: 2x � 6y = 42 3x � 9y = -15 I am to solve similar systems of equat

Question 147216: When solving a system of equations, how do I know what numbers to put in place of x and y? An example is:

2x � 6y = 42
3x � 9y = -15
I am to solve similar systems of equations but I do not understand what nubers to replace the variables with.
Can you help?
Thank you very much.

Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!

Start with the given system of equations:

Multiply the both sides of the first equation by -3.

Distribute and multiply.

Multiply the both sides of the second equation by 2.

Distribute and multiply.

So we have the new system of equations:

Now add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:

Group like terms.

Combine like terms. Notice how the x terms cancel out.

Simplify.

Since is never true, this means that there are no solutions. So the two equations are inconsistent.

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