Question

How can you say that the points $(1,-5),(3,-2),(7,4)$ are collinear?

Answer 1

(1,-5)(3,-2)

$y+5=\frac{-2+5}{3-1}(x-1)$

$2y+10=3x-3$

2y=3x-13

for, collinearty (7,4)must satisfy.

$\therefore 2\times 4=3\times 7-13$

8=8

$\therefore$ all there point are collinear