SOLUTION: Find “a” given that P(-3,4), Q(2,6) and R(5,a) are collinear with proper steps.

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Question 1108574: Find “a” given that P(-3,4), Q(2,6) and R(5,a) are collinear with proper steps.
Answer by Edwin McCravy(20067) About Me  (Show Source):
You can put this solution on YOUR website!
PQ, PR and QR are all segments of the same line, so they
all three must have the same slope:

We can pick any any two pairs of the three point, use the
slope formula on both pairs, set the two expressions for
the slope equal to each other, and solve for "a".

If we pick PQ and PR

 

Solve for a

Edwin