Question

The points (-5, 1), (1, p) and (4, -2) are collinear if the value of p is? A 3 B 2 C 1 D -1

Answer 1

Answer:

C) 1

Step-by-step explanation:

If three points are collinear then the area of the triangle formed by them is 0

∴ 0.5|x₁(y₂-y₃) +x₂(y₃-y₁) +x₃(y₁-y₂)| =0

⇒0.5|[(-5)(p-(-2))]+[1((-2)-1)]+[4(1-p)] =0

⇒|-5p-10-3+4-4p|=0

⇒|-9p-9|=0

∴p=1

∴The correct answer is C

Hope this will help you.

Answer 2

Step-by-step explanation:

: Reason: The points are collinear if area of Δ = 0

= 12[-5(p + 2) +l(-2 -1) + 4(1 – p)] – 0

⇒ -5 p -10-3 + 4-4p = 0

⇒ -9p = +9

∴ p = -1