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

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sodelete | Student, College Freshman | (Level 1) Honors

Posted May 1, 2011 at 10:00 AM via web

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common point

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

 

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted May 1, 2011 at 11:51 AM (Answer #2)

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At the common point of the lines x+y=4 and 2x=y-2, the x and y coordinates are equal.

2x = y - 2

=> y = 2x + 2

substitute in x + y = 4

=> x + 2x + 2 = 4

=> 3x = 2

=> x = 2/3

y = 4 - 2/3 = 10/3

The common point of the lines is (2/3, 10/3)

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted May 2, 2011 at 7:41 AM (Answer #3)

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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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