Please Help!! Fan and Medal!
Problem - Solve using two different methods! Explain which method you found to be more efficient?
A -
3x - 9y = 3
6x - 3y = -24

Thank you!

Question

Please Help!!  Fan and Medal!
Problem - Solve using two different methods! Explain which method you found to be more efficient?
A - 
3x - 9y = 3
6x - 3y = -24

Thank you!

shiree19 · Answer

@SolomonZelman @humphriescody

anonymous · Answer

I do not now sorey good luck thow

shiree19 · Answer

Thanks anyway.  :)

shiree19 · Answer

@Loser66 @scburchell11

shiree19 · Answer

Please help!  Anyone?

anonymous · Answer

(a) elimination :
 3x - 9y = 3 ---->(-2)
  6x - 3y = -24
--------------
-6x + 18y = -6 (result of multiplying by -2)
6x - 3y = -24
-------------add
15y = - 30
y = - 2
sub in -2 for y
3x - 9y = 3
3x - 9(-2) = 3
3x + 18 = 3
3x = -18 + 3
3x = - 15
x = - 5

substitution
3x - 9y = 3
3x = 9y + 3
x = 9/3y + 3/3
x = 3y + 1
now sub 3y + 1 in for x
6x - 3y = -24
6(3y + 1) - 3y = -24
18y + 6 - 3y = -24
18y - 3y = -24 - 6
15y = -30
y = -2
now sub -2 in for y
3x - 9y = 3
3x - 9(-2) = 3
3x + 18 = 3
3x = 3 - 18
3x = -15
x = -5

shiree19 · Answer

Ok but how did you get -2 for y?
And did you use Substitution for both of them?

anonymous · Answer

explained in now sub 3y + 1 in for x

shiree19 · Answer

So there would be 2 y's?
That doesn't really make sense.

shiree19 · Answer

Well if 3y + 1 = -2 = y
is that right?

anonymous · Answer

yes

shiree19 · Answer

Ok.  So the answer for 3x - 9y = 3  is
x = -5 & y = -2
and we used the Substitution method.
Is that correct?

anonymous · Answer

yes

shiree19 · Answer

So what method do we use to solve 6x - 3y = -24?  As we can't use the same method.

anonymous · Answer

yes

shiree19 · Answer

What method would be best?
Maybe elimination?

anonymous · Answer

that is the answer for both

shiree19 · Answer

Yes, but I have to use a different method for each problem.

anonymous · Answer

this one is the best I will try to finesh the uther one

shiree19 · Answer

Using elimination - 
if y = -2
then to solve x
6x - 3 * -2 = -24
divide both sides by 6
x - 3 * -2 = -4
divide both sides by -2
x - 3 = -2
add 3 to both sides
x = -5

So, x = -5 and y = -2
This is right, yes?

anonymous · Answer

that is it

shiree19 · Answer

Ok.  Thanks so much!

anonymous · Answer

ok you are welcome

anonymous · Answer

do you need more help

shiree19 · Answer

Yes please.  Sorry for the wait I was trying to figure it out on my own.
Same rules apply.
7x - 3y = 20
5x + 3y = 16

shiree19 · Answer

I think I figured it out.