Question

Solve using two differemt methods. Explain which method you found to be more efficient.

a. 3x-9y=3
6x - 3y= -24

Answer 1

The two methods are elimination and substitution.

Answer 2

There is also graphing

Answer 3

What have you tried?

Answer 4

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

Answer 5

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

Answer 6

Ok

Answer 7

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

Answer 8

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

Answer 9

No.

Answer 10

oh

Answer 11

well, how do i do it?

Answer 12

Do it simultaneously.

Answer 13

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

Answer 14

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

Answer 15

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

Answer 16

\[-3y+18y=-30\]
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.

Answer 17

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