Question

Precalc, please help?

Find the parametric equations for the line passing through points at (-1/3, 1, 1) and (0, 5, -8). (Hint: equations are needed for x, y, and z)

The answer is: x=-1/3+1/3t, y=1+4t, z=1-9t

How do I find this answer?

Answer 1

@phi

Answer 2

I always think of these as
P = P0 + t*V
where P0 is the starting point, and V is the direction
to find V, subtract the two points they give you.

we have choices here. They used (-1/3, 1, 1) as the starting point

Answer 3

(0, 5, 8)-(-1/3, 1, 1)=(1/3, 4, 7)

So I can see how to get the equations for x and y, but I don't understand how to find the equation for z.

Answer 4

if you use the numbers they gave you, you would have better luck
(0, 5, -8) <-- notice -8

Answer 5

Ahh I see I missed the negative. Haha thank you!