ok i know how to this but i donno if i did right

3y-x=3 and 4x+3y-18=0

-solve by graphing

-solve using algebra

-and formal check

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- Feb 20th 2006, 04:15 PM #1

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- Feb 20th 2006, 08:56 PM #2Originally Posted by
**usm_67**

to graphing: I've attached a drawing. The coordinates of the intersection is the solution you're looking for.

to using algebra: There are at least 4 to 5 different method to get a solution:

Both values of y must be equal:

and that means: x = 3

Put x = 3 in one the equations:

So you get the intersection at (3,2)

to formal check: Put x=3 and y=2 in your original equations:

you'll get 3=3 and that's true.

You'll get: 12 + 6 -18=0 and that's true.

Greetings

EB

- Feb 21st 2006, 04:41 PM #3

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- Feb 22nd 2006, 10:31 AM #4Originally Posted by
**usm_67**

here I'm again. Of course you're right. But as I mentioned before there are many different methods. So if you have to use elimination and substitution, you can do it like this:

Put this value of y into the 2nd equation to eliminate the variable y:

Simplify this equation and you'll get: 5x - 15 = 0. That means: 5x = 15 and so x = 3

Put this value into the 1rst equation and you'll get y = 2

And that's the result you've got before.

It doesn't matter which method you use, all of them come to the same solution.

Greetings

EB