Homework Help: Linear algebra, parametric equation, intersectin of line

1. Mar 5, 2009

cleopatra

1. The problem statement, all variables and given/known data

Two equations for two planes in 3-D
2x+y-2z=1
x-2y+z=-3
Find the parametric equation for the line of intersection of the two planes by solving these two equations togeather.

3. The attempt at a solution

Gauss Jordan gives:
1 0 -3/5 -1/5
0 1 -4/5 7/5

if z=t
x=3/5t-1/5
y=4/5t+7/5

I don´t know how to finish the problem.

Last edited: Mar 5, 2009
2. Mar 5, 2009

yyat

You have already solved the problem!

x=3/5t-1/5
y=4/5t+7/5
z=t

is the parametric equation for the intersection.

Last edited: Mar 5, 2009
3. Mar 5, 2009

Dick

You are already finished. z=t, x=(3/5)t-1/5 and y=(4/5)t+7/5 is the intersection line in parametric form. Are you supposed to express it in vector form or something?

4. Mar 5, 2009

cleopatra

really? I thought this was only the parametric equation and I had to find some special line of intersection as well.

5. Mar 5, 2009

Dick

Nah. The problem says find the line that is the intersection of the two planes. No line intersection involved.

6. Mar 5, 2009

cleopatra

okey thanks for that