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What is the point of intersection of x + 3y + 8 = 0 and x - 7y + 9 = 0

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xetaalpha | Student | Honors

Posted August 7, 2011 at 11:42 PM via web

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What is the point of intersection of x + 3y + 8 = 0 and x - 7y + 9 = 0

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted August 7, 2011 at 11:52 PM (Answer #2)

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Let the point of intersection of x + 3y + 8 = 0 and x - 7y + 9 = 0 be (X, Y). This gives us the following set of simultaneous equations to solve for X and Y:

X + 3Y + 8 = 0 ...(1)

X - 7Y + 9 = 0 ...(2)

(1) - (2)

=> 3Y + 7Y + 8 - 9 = 0

=> 10Y = 1

=> Y = 1/10

substitute Y in (1)

X + 3/10 + 8 = 0

=> X = -8 - 3/10

=> X = -83/10

The point of intersection of the two lines is (-83/10, 1/10)

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