Sketch the line segment represented by each vector equation:
$\begin{align} r &= (1-t)(i+j) + tk \;& 0 \le t \le 1 \\ \\ r &= (1-t)(i+j+k) + t(i+j) \;& 0 \le t \le 1 \end{align}$
I'm having a really hard time trying to figure this out. I'm in my textbook and the only thing it has on this topic is
$r = r_{0} + t(r_{1} - r_{0})$ or $r = (1-t)r_{0} + tr_{1}$
It doesn't give any examples on how to graph the line segment. (I've even looked in the back of the book on previous similar problems not assigned to me, and they don't give any clues on why they are graphed the way they are...)
Could someone help explain this to me?