Find the x, y?

Question

x + 2y = 4
x - 2y = 0

Answer 1

x + 2y = 4 (eq 1)
x - 2y = 0 (eq 2)

add equations 1 and 2 together

x+x +2y -2y =4

2x =4

x=4/2=2

Substituting this into equation 2
2y=x,

y= x/2 = 2/2 = 1.

x=2, y=1

Answer 2

y=1 x=2

Answer 3

x + 2y =4
x - 2y = 0

well,

x + 2y = 4
x = 4 -2y

sub into the other equation,

(4 - 2y) -2y = 0
4 - 2y - 2y = 0
4 = 4y
1 = y

sub y = 1 into an equation to find x which gives us,
x - 2(1) = 0
x -2 = 0
x = 2

therefore (x,y) = (2 , 1)

Answer 4

x=2 and y=1

Answer 5

You add both equations:
x+2y+x-2y=0+4 =>
2x=4=>
x=4:2=>
x=2

Now you get back to one of the equations, lets take the first. Substitute x with 2:
2+2y=4=>
2y=4-2
2y=2 =>
y=2:2 =>
y=1 =>

Answer 6

x + 2y = 4- - - - - -Equation 1
x - 2y = 0- - - - - - Equation 2
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2x = 4

2x / 2 = 4 / 2

x = 4 / 2

x = 2

Insert the x value into equation 2

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x - 2y = 0

2 - 2y = 0

2 - 2y - 2 = 0 - 2

- 2y = - 2

- 2y / - 2 = - 2 / - 2

y = - 2 / - 2

y = 1

Insert the y value into equation 2

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Check for equation 2

x - 2y = 0

2 - 2(1) = 0

2 - 2 = 0

0 = 0

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Check for equation 1

x + 2y = 2

2 + 2(1) = 2

2 + 2 = 4

4 = 4

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Both equations balance

The solution set is { 2, 1 }

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Answer 7

x + 2y = 4:
x = 4 - 2y
4 - x / 2 = y

x - 2y = 0
x = 2y
y = -x / -2 = x/2