which is the solution to the system of equations? 3x plus y equals -2 4x plus 12y equals 8?

Question

can i use substitution or combination or elimination and how??

Answer 1

3x + y = -2
4x + 12y = 8

I would use substitution. Take the first equation and solve for y.

y = -3x - 2

Now plug in (-3x - 2) into the second equation.

4x + 12(-3x - 2) = 8

Solve for x.

4x -36x - 24 = 8
-32x = 32
x = -1

After this you plug -1 into either equation and solve for y. I am going to use the first equation.

3x + y = -2
3(-1) + y = -2
-3 + y = -2
y = 1

Using the second equation:
4x + 12y = 8
4(-1) + 12y = 8
-4 + 12y = 8
12y = 12
y = 1

So your answer is (-1,1)

Answer 2

i would re-arrange the equation and then substitute it in

3x + y = -2 ---> y = -3x - 2

substitute into the other equation

4x + 12y = 8
4x +12(-3x - 2) = 8
4x + -36x - 24 = 8

let equation equal 0
4x - 36x - 24 - 8 = 0
-32x - 32 = 0

factorize to find x number
-32(x + 1) = 0
x + 1 = 0
x = -1

find y number
y = -3x - 2
y = (-3 x -1) - 2
y = 3 - 2
y = 1

Point of intersection of these two lines would be
(-1,1)

Hope this helps - i think i have done something which you didn't ask for!
If you don't understand it just leave it lol!

Answer 3

You can use substitution. So

4x + 12y = 8
So 4x = 8 -12y.

In the other equation
3x + y = -2
so 3x = -2 -y
x = -2-y/3

4x = 4 x (-2-y) so
-8 - 4y + 12y = 8
8y = 8 + 8 = 16
y =2
So
3x + y = -2
3x + 2 = -2
3x = -4
x = -4/3

Answer 4

hmm... i'd use elimination. so i think these are your equations:

3x + y = -2
4x+ 12y = 8

so muliply the first equation by -12, and then add it to the second equation to get rid of the y's.

-12 * (3x + y) = 24 => -36x -12y = 24

-36x+ 4x - 12y +12y = 8 + 24
-32 x = 32
x= -1

Answer 5

3x+y==-2
4x+12y=8

y=-2-3x

4x+12(-2-3x)=8
4x-24-36x=8
-32x-24+24=8+24
-32x=32
x=-1

-3+y=-2
y=1 use substitution here it is easier

Answer 6

Get it into y=mx+b form?