David Z.

asked • 04/19/19

2x+4y=20,-3x+4y=30 elimination

David Z.

i need help on thiss
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04/19/19

Robert C.

tutor
First, eliminate X. Do this by multipying both sides of the 1st equation by 3/2. This will yield 3x +6y = 30. Then add both equations together. This will yield 10y = 60, so y=6. Substitute 6 for y into the 1st equation, (you could do this with either), and you get 2x+ 24= 20. Simplify, 2x =-4, so x=-2. The solution in x=-2, y=6. I hope this helped!
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04/19/19

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Brenda D. answered • 04/22/19

Tutor
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Math's a tool not a terror

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Try multiplying the first equation by negative 1

Then combine the equations

Solve for the remaining variable


2x + 4y = 20

-3x + 4y = 30


If you multiply 2x + 4y = 20 by negative one you get -2x - 4y = -20 then you will have


-2x - 4y = -20

-3x + 4y = 30


Combine those above and the y is easily eliminated and you have


-5x = 10

Divide both sides by -5 and you have

x = -2

Just plug that into the second equation to solve for y; you should get 6.

Then just plug the numbers in the original equations to check.


Give it a try

I hope this helps

If you have any questions just send me a message.




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