Question

If three points (5,1) , (1,-1) and (m,4) are collinear.Find m​

Answer 1

m = 11

Explanation:

Since the points are collinear then the slope between points are equal.

Calculate the slope m using the slope formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (5, 1) and (x₂, y₂ ) = (1, - 1)

m =
`(-1-1)/(1-5)` =
`(-2)/(-4)` =
`(1)/(2)`

Repeat with

(x₁, y₁ ) = (1, - 1) and (x₂, y₂ ) = (m, 4)

m =
`(4+1)/(m-1)` =
`(5)/(m-1)` =
`(1)/(2)`

Cross- multiply

m - 1 = 10 ( add 1 to both sides )

m = 11