Co-linear question?????????? (1 Viewer)

omgiloverice · Jul 22, 2012

If points (-3k,1), (k - 1, k - 3) and (k - 4, k - 5) are collinear, find the value of k .

Btw the answer is -2 x_x
any answer on why?

Sy123 · Jul 22, 2012

$$Call the points$ \ \ A(-3k,1) \ \ B(k-1, k-5) \ \ C(k-4, k-5) \\ \\ m_{AB}=m_{BC} \ \ $Collinear points where m refers to gradient$ \\ \\ \frac{k-3-1}{k-1+3k}=\frac{k-5-k+3}{k-4-k+1} \\ \\ \frac{k-4}{4k-1}=\frac{2}{3} \\ \\ 3k-12=8k-2 \\ k=-2$

I just evaluate the gradients of AB and BC. Because we know they are collinear their gradients are equal.

Co-linear question?????????? (1 Viewer)

omgiloverice

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Sy123

This too shall pass

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