##### Solving systems of linear equations

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y-x+7         7   8   9   10

y=9-x         9   8   7  6

Solutions to both equations is (ordered pair)

Sep 12th, 2015

Chrissy,

I assume that the first line is actually y = x + 7. If not, then you don't have a SYSTEM of linear equations.

First off, if y = x+7 and y = 9-x, then (since y = y)

x + 7 = 9 - x. Adding x to both sides yields 2*x + 7 = 9. Subtracting 7 from both sides yields 2x = 2, so x = 1. Since x = 1 is not one of the available values, this means that one or the other (or both) of the two equations is misstated.

Let's try assuming that y - x = 7. Adding x to both sides yields y = 7 + x. So if y = y, then 7 + x = 9 - x and so

adding x to both sides yields 7 + 2x = 9, and 2x = 2, as before.

You need to check the expressions in column 1. Let me know what you discover and we can solve the problem.

Sep 12th, 2015

it is y=x+7.. I type fast.

Sep 12th, 2015

Ok. If the first equation is y = x+7 and the second equation is y = 9-x, then (as I showed earlier), x must equal 1. But 1 is not an available value for x. Or is it?

Can you check to see if the number 10 is actually a 1 followed by a zero.

If it isn't then none of the possible (x,y) pairs will satisfy both equations.

Sep 12th, 2015

It is a "10"

Sep 13th, 2015

The none of  available ordered pairs will be a solution to the system. You could try all of them, but I wouldn't recommend it. The mathematics is airtight. Best wishes.

Sep 13th, 2015

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Sep 12th, 2015
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Sep 12th, 2015
Dec 9th, 2016
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