Question 1209384
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The three points are collinear if the slope of the line containing (4,2) and (8,10) is the same as the slope of the line containing (8,10) and (11,16).<br>
Of course you can use the formal formula for finding the slope of the line containing two points.  But in my opinion it is more educational to use the informal "rise over run" definition of slope.<br>
Between (4,2) and (8,10) the run is 8-4=4 and the rise is 10-2=8; the slope is rise/run = 8/4 = 2.<br>
Between (8,10) and (11,16) the run is 16-10=6 and the rise is 11-8=3; the slope is rise/run = 6/3 = 2.<br>
The slopes are the same, so the three points are collinear.<br>