SOLUTION: hi, i need to solve this using elimination method and check. 4x+y=1 x-2y=-2

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Question 147698This question is from textbook
: hi, i need to solve this using elimination method and check.
4x+y=1
x-2y=-2
This question is from textbook

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

Start with the given system of equations:



Multiply the both sides of the first equation by 2.


Distribute and multiply.


So we have the new system of equations:



Now 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.


Remove any zero terms.


Divide both sides by to isolate .


Reduce.


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)


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

Check:


Start with the first equation.


Plug in and .


Evaluate and simplify the left side.


Since the equation is true, this means that (0,1) is a solution for the first equation.


Start with the second equation.


Plug in and .


Evaluate and simplify the left side.


Since the equation is true, this means that (0,1) is a solution for the second equation.


Since all of the equations of the system are true, this means that (0,1) is a solution of the system. So this verifies our answer.

Answer by GKelly(4)   (Show Source): You can put this solution on YOUR website!
First, multiply the first equation 4x + y = 1 by 2. You'll end up with the following:
2(4x + y =1); 8x + 2y = 2. Now you may eliminate the 2y; see below
8x + 2y = 2
x - 2y = -2
Cancel out the 2y. You will now have 9x = 0 so X = 0
Now, plug 0 into the x value in the first equation so you can then solve for y.
4x + y = 1
4(0) +y = 1
0 + y = 1
y = 1 - 0
y = 1
X = 0 and y = 1
Now plug in these values into the first equation:
4x + y = 1
4(0) + 1 = 1
0 + 1 = 1
1 = 1 YOU'RE DONE.

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