Question 206413:  Hi all, I was hoping someone could show me how to solve the following, 
Find the equation of the line that contains points (2,1,-3) and (-1,4,1) 
Help with steps on how to solve would be great, 
Thanks, -nick. 
 Answer by Edwin McCravy(20064)      (Show Source): 
You can  put this solution on YOUR website! 
I did this problem for you recently, Nick.  Here it is again.
Is there something about it that you didn't understand about
lines in space?  Would you understand it better if I used
the i,j,k notation instead of the ‹a,b,c› notation? 
If you need further help, you may email me at AnlytcPhil@aol.com
A line parallel to the vector v = ‹a,b,c› and passing through the
point P( , , ) is represented by the
parametric equations
 ,  ,  
or as the symmetric equations:
 
if none of a,b, or c are 0.
Begin by using the points P(2,1,-3) and Q(-1,4,1) 
to find a direction vector for the line passing through 
P and Q, given by
    __
v = PQ = ‹-1-(2),4-1,1-(-3)› = ‹-3,3,4›
So we substitute in 
 ,  ,  
with ‹a,b,c› = ‹-3,3,4›  and the point P( , , ) = P(2,1,-3)
 ,  ,  
That's the parametric equations for the line.
If you want the symmetric equation of the line, we
substitute in
 
 
 
Edwin  
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