Question

Find the equation of the line passing through the points 7,2 and 9,1

Answer 1

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Answer:

  y = -1/2x +11/2

Step-by-step explanation:

The slope of the line is ...

  m = (y2 -y1)/(x2 -x1)

  m = (1 -2)/(9 -7) = -1/2

The y-intercept is ...

  b = y -mx

  b = 2 -(-1/2)(7) = 11/2

Then the slope-intercept equation is ...

  y = -1/2x +11/2

_____

Alternative solution

A general form equation for the line can be ...

  (y1 -y2)(x -x1) -(x1 -x2)(y -y1) = 0

  (2 -1)(x -7) -(7 -9)(y -2) = 0

  x-7 +2y -4 = 0

  x +2y -11 = 0 . . . . . general form equation

  x +2y = 11 . . . . . . . standard form equation

Note that we want the x-coefficient to be positive, so we chose the order of the points to make that be the case.