The points (1, 7), (2, 4) and (k, 1) are collinear. The value of k is:
Answer: A
For the points to be collinear, the slope between the first two points must equal the slope between the second and third points.
Slope between (1, 7) and (2, 4) = \(\frac{4-7}{2-1} = \frac{-3}{1} = -3\).
Slope between (2, 4) and (k, 1) = \(\frac{1-4}{k-2} = \frac{-3}{k-2}\).
Set the slopes equal: -3 = \(\frac{-3}{k-2}\).
This implies k-2 = 1, so k = 3.