Solve the system of linear equations below:

x - 3y = -3
x + 3y = 9

Question

Solve the system of linear equations below:

x  -  3y  =  -3
x  +  3y  =  9

anonymous · Answer

A) x  =  -12, y  =  7

B) x  =  3, y  =  2

C) x  =  6, y  =  1

D) x  =  6, y  =  2

anonymous · Answer

c

anonymous · Answer

Can you explain it please

igreen · Answer

@otakukid99 Don't give answers.

igreen · Answer

We can solve by substitution.

First, we can rearrange the first equation.

$x - 3y = -3$

Now we add 3y to both sides:

$x = -3 + 3y$

Okay, now we can plug in $-3 + 3y$ for $x$ in the 2nd equation.

$x + 3y = 9$

$-3 + 3y + 3y = 9$

Can you simplify that? @TheYoungBlaze

igreen · Answer

We're solving for $y$.

anonymous · Answer

-3 + 6y = 9
Add 3 to both sides to get rid of the -3
So 6y = 12
Divide by 6
1y = 2

Right? Or no?

igreen · Answer

Yep!

igreen · Answer

So $y = 2$.

Now we can plug in 2 for y into any of the two original equations:

$x  +  3y  =  9$

$x + 3(2) = 9$

Can you solve for $x$?

igreen · Answer

@TheYoungBlaze

anonymous · Answer

x + 6 = 9
6x = 9
Divide by GCF which is 3
2x = 3

igreen · Answer

Um..no.

$x + 6 = 9$

Just subtract 6 to both sides..what do you get? @TheYoungBlaze

anonymous · Answer

Ah I have a tendency to overthink things. I knew the answer sounded wrong.
x = 3

So:
y = 2
x = 3

igreen · Answer

Yep.

igreen · Answer

Just remember, we do the opposite..$x + 6 = 9$. Notice that 6 is being ADDED to $x$. To undo addition, we do the opposite of addition, which is subtraction..not Division or Multiplication.