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## Homework Statement

Find cartesian equations of the line L containing P(2, 0, -3) and Q(1, -1, 6) and determine if plane (8x + y - z = -1) is perpendicular to L

## Homework Equations

## The Attempt at a Solution

PQ = (1-2)i + (-1-0)j + (6+3)k = -i -j +9k

(x-2)i + (y-0)j + (z+3)k = -ti - tj +9tk

so, cartesian equation of L is:

[tex]\frac{x-2}{-1} = \frac{y}{-1} = \frac{z+3}{9}[/tex]

The plane normal n = (8, 1, -1). If dot product n and L = 0 then they are perpendicular.

How do I take the dot product of L and n in that form?

I don't understand the general equation of the line, I just followed an example and plugged in some numbers. This question should take about 5 minutes but has taken me about 2 hours and I still have no clue.