Vector Equations to scalar equation and back

• Mar 21st 2013, 12:24 PM
flammingKnife95
Vector Equations to scalar equation and back
the problem is

1. Find vector and parametric equations for the line with equation 2x + y + 3 = 0.
2. Determine a scalar equation for the line that passes through the point (-1, 5) and has direction vector http://mathhelpforum.com/MCV4UPU02/M...es%2Fvec-m.gif = (1, −3).

I am taking this coarse online and the content is no help please show me how it is done
Thanks
• Mar 21st 2013, 02:39 PM
MINOANMAN
Re: Vector Equations to scalar equation and back
FlammingKnife

consider the line in 2D ax+by+c=0. Then the vector (-b,a) is always // to this line. you must know this....
to find the parametric equation of a line you need the vector // to the line and one point of the line.
in your case get one point of the line...example put x = 1 and find the y = -5

therefore the parametric equations of the line 2x+y+3=0 are x= 1-t and y = -5 +2t.

you may work similarly for the second question

MINOAS