## anonymous 3 years ago Solve using two differemt methods. Explain which method you found to be more efficient. a. 3x-9y=3 6x - 3y= -24

1. anonymous

The two methods are elimination and substitution.

2. anonymous

There is also graphing

3. skullpatrol

What have you tried?

4. anonymous

Nothing yet, i know how to do elimination. But i dont know how to substitution or graphing.

5. skullpatrol

Use elimination and find the answer first. All the methods should give the same answer, right?

6. anonymous

Ok

7. skullpatrol

$$3x-9y=3$$ $$6x - 3y= -24$$

8. anonymous

I got 3x-6y= -27 but i dont think its rigth is it?

9. skullpatrol

No.

10. anonymous

oh

11. anonymous

well, how do i do it?

12. anonymous

Do it simultaneously.

13. skullpatrol

You said you know how to use elimination. Try multiplying the first equation by $$-2$$ and add it to the second equation...

14. skullpatrol

$$(3x-9y=3) (-2)$$ 6x - 3y= -24

15. anonymous

$3x-9y=3 [1]$ $6x - 3y= -24 [2]$ $2\times [1]$ $6x-18y=6 [3]$ $[2]-[3]$ $(6x - 3y) - (6x-18y)= (-24)-(6)$

16. anonymous

$-3y+18y=-30$ The x's cancel out. Now you can solve for y. Once you solve for y, you can then substitute the y component that you just found, into any one of the equations above to find your x-value.

17. anonymous

If you need further assistance, I will be happy to elaborate it in more simple terms.