If the x-coordinate of a point `P` on the jon of `Q(2,2,1)` and `R(5,1,-2)` is 4, then its z-coordinate is

Options

A. `-2`
B. `-1`
C. 1
D. 2

Answer

B

Explanation

Suppose P divides QR in the ratio `lambda : 1` . Then coordinates of P are
`((5lambda+2lambda)/(lambda+1),(2lambda +2)/(lambda +1),(-2lambda +1)/(lambda +1))`
Since, the coordinate of P is 4.
i.e., `(5lambda + 2)/(lambda +1) =4 rArr lambda = 2`
So , Z- coordinate of P is
`(-2lambda +1)/(lambda+1) = (-4 +1)/(2+1) = - 1`