Find the common point of the lines x+y=4 and 2x=y-2.

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justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

We have the two lines x+y=4 and 2x=y-2.

Now at the common point, both the values of y and x are the same.

x+y=4

=> x = 4- y

substitute this in 2x=y-2

=> 2(4 - y) = y - 2

=> 8 - 2y = y - 2

=> 3y = 10

=> y = 10/3

Substitute y = 10/3 in x = 4- y

=> x = 4- 10/3

=> x = 2/3

Therefore the common point is (2/3, 10/3)

Top Answer

giorgiana1976's profile pic

giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted on

To determine the common point of the lines, we'll have to solve the system of the equations of the given lines.

We'll solve the system using substitution method. We'll change the 2nd equation into:

x+y = 4

x = 4 - y (3)

We'll substitute (3) in (1):

2(4 - y)  = y -2

We'll remove the brackets and we'll subtract y both sides:

8 - 2y - y = -2

We'll combine like terms and we'll subtract 8 both sides:

-3y = -2 - 8

-3y = -10

We'll divide by -3:

y = 10/3

We'll substitute y in (3):

x = 4 - 10/3

x = (12-10)/3

x = 2/3

For the common point: The solutions of the system represents the coordinates of the intercepting point of the lines: {(2/3 ; 10/3)}.

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