1. The problem statement, all variables and given/known data Say that I have a problem along the lines of: Find the point-normal equation for the line L. L=u1+k*u2, where k is ℝ. And then I'm given u1 and u2, which both are 2×1 vectors. Then L will also be a 2×1 vector (which consists of a11 and a21), which I guess is ok (since it gives the two coordinats in R2). However the point-normal equation is in the form of (for some constants a and b and some points x0 and y0 on the line L): a(x-x0)+b(y-0)=0. So here comes my question: In the vector L: Are a11 or a21 x? 2. Relevant equations - 3. The attempt at a solution See above.