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The points (a,1), (9,0), and (-3,4) lie on a straight line.  Find a.

 Jun 6, 2020
 #1
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The slope of the line is    (y1-y2)/ (x1-x2) = (0-4)/(9--3) = -4/12 = -1/3

 

The slope between   a,1    and either of the other two poins must equal  - 1/3

 

(0-1)/(9-a) = - 1/3

-1/(9-a) = -1/3

 

-1/(-1/3) = 9-a

3 = 9-a        a = 6

 Jun 6, 2020

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