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Solving linear equations simultaneously. Example:

4x-2y=85

2x+4y=136

 

Hi guys,

I am having a bit of trouble with solving linear equations and I can't seem to understand the explanations as well, considering that Math is my most least favored subject. Could you guys please help me?

 

Thanks,

Guest May 9, 2017
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4x – 2y = 85

2x + 4y = 136

 

On these, we can use the "elimination" method, where we line the two given equations up and add straight down. We could do that right now..but it won't yield a useful equation. We want one of the variables to go away when we add straight down. So let's multiply the top equation through by 2.

2(4x – 2y) = 2(85)

8x – 4y = 170

 

Now line this up with the second equation given and add straight down.

   8x – 4y = 170

+ 2x + 4y = 136

  10x + 0y = 306

 

10x = 306

x = 306/10

x = 30.6

 

Now we have found what x is!

Use this new found value for x in either equation to find what y is.

4(30.6) - 2y = 85

122.4 - 2y = 85

-2y = 85 - 122.4

-2y = -37.4

y = -37.4/-2

y = 18.7

hectictar  May 9, 2017

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