## ValentinaT 3 years ago Using substitution, could someone please help me with this system? –y + 3x = 6 y = –6x + 12 So far I've gotten: Substituting the second equation into the first you get -(-6x+12) + 3x = 6 Which can be solved for x after finding x you can use the second equation above directly to find y

Sounds like you know what you are doing .... What's the problem you are having?

2. ValentinaT

Well, I had help with that part, but I can't figure out what to do next. I tried using my textbook, but it was a bit confusing, because they showed you what to do, but didn't explain it.

Ok, first let's distribute that -(-6x+12) Can you do that?

4. ValentinaT

-6x + -72?

Think of it this way: (-)(-6x) & (-)(12)

6. ValentinaT

Because negative times negative equals a positive 6x + -12?

yes, very good so we have 6x-12+3x=6 What will you do next?

8. ValentinaT

correct 9x-12=6 now what?

10. ValentinaT

Substitute for y from the other equation?

Let's try to solve for x.

12. ValentinaT

Sorry, I was looking at my textbook, and thought that we were onto that step.

:-) That's ok.

14. ValentinaT

Okay, so how would I go about solving for x? Also, thank you for the medal.

We have x on one side, can we get non x-values on the other side?

16. ValentinaT

You would add 12 + 6? Then get 18, divided by 9x would equal 2.

Excellent: So x=2

18. ValentinaT

Okay.

What are you going to do with that x=2?

You still there?

21. ValentinaT

Substitute 2 for x in either equation and solve for y? Sorry, my computer is slow sometimes.

Heh I Understand. You are correct, good job!

23. ValentinaT

Thank you! So, -y + 3(2) + 6.

-y+3(2)=6

25. ValentinaT

So, -y + 6 = 6.

correct

27. ValentinaT

What would I do next?

same that you did when you had 9x-12=6 and solved for x. now we are going to it for y

29. ValentinaT

6 - 6 = 0 So y, would be 0?

That is correct.

31. ValentinaT

Then I would substitute 0for y, and get 0 + 6 = 6.

As long as you get a correct statement when you plug them both back in, like you showed 6=6 and not get something like 7=6, then we would have a problem.

34. ValentinaT

Okay, thank you some much for your help. If I could give you more than one medal I would.

Thank you, It is nice to meet someone who wants to work out the problems and not just demand an answer.

36. ValentinaT

I get what you mean, you are a very good teacher by the way.