SOLUTION: i need step by step solution using elimination x+y=-12 x-y=-4

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Question 148094This question is from textbook
: i need step by step solution using elimination
x+y=-12
x-y=-4
This question is from textbook

Found 2 solutions by jim_thompson5910, mangopeeler07:
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!

Start with the given system of equations:



Add the equations together. You can do this by simply adding the two left sides and the two right sides separately like this:





Group like terms.


Combine like terms. Notice how the y terms cancel out.


Simplify.


Divide both sides by to isolate .


Reduce.


------------------------------------------------------------------


Now go back to the first equation.


Plug in .


Multiply.


Add to both sides.


Combine like terms on the right side.


So our answer is and .


Which form the ordered pair .


This means that the system is consistent and independent.


Notice when we graph the equations, we see that they intersect at . So this visually verifies our answer.


Graph of (red) and (green)

Answer by mangopeeler07(462)   (Show Source): You can put this solution on YOUR website!


Since the y's in the expressions are opposites, then just add the expressions to each other to eliminate the y variable from the jump.


+
----------------


Then divide both sides by 2


Then to get y, plug x back into one of the original equations or
. Doesn't matter which one. How about .

Plug in -8 for x
.

Then add 8 to each side
.

Plug both values into the other original equation .
or . It's true.

Therefore,
x=-8
y=-4

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