Question

for what value of K (k,11) (1,5) (-1,1) are collinear

Answer 1

 As they are collinear, m1 = m2 (slopes)
Therefore, (y2-y1) / (x2-x1) = (y3-y2) / (x3-x2) 
(5-11) / (1-k) = (1-5) / (-1-1)
-6/(1-k) = -4 / -2
-6/(1-k) = 2
-6 = 2(1-k)
-6 = 2-2k
2k=2+6
2k=8
k=4

Answer 2

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