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If 2x + y = 9 and 2x – y = 11 , what is the value of x?

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Mlcparra16id
Here is a simple way of solving it
We let:
2x + y = 9 ... [1]
2x - y = 11 ... [2]

[1]-[2]
2x + y =9
-2x -(-y) = -11
2y=-2
y=-1

We just substitute this to one of the equations:
2x-1=9
2x=10
x=5

You can actually just do [1]+[2]

 2x +y =9
+2x -y =11
   4x =20 
    x=5
Jers15id
2x+y=9
2x-y=11

Using elimination method, remove y
4x=20
Divide both sides by 4
x=5

Now to solve y, just substitute the value of x to any equation
2x+y=9
2(5)+y=9
10+y=9
Subtract both sides by 10
y=-1

Hope this helps =)