 
Summary: Math 151
Spring 2000
Common Exam 1
Key to Version A
1. Consider the line whose vector equation is r (t) = (2  3t) i+(1  t) j
Which vector is parallel to this line?
(a) 2, 1 (b) 3, 1 (c) j (d) (1  t) j (e) i
The easiest way to do this problem is to rewrite the expression for
r (t).
r (t) = (2, 1) + t (3, 1)
Thus, (3, 1) is parallel to the line.
2. Find a unit vector which points in the same direction as 1, 5 .
(a) 1, 5 (b) 1, 5 (c)
1, 5
26
(d)
1, 5
26
(e)
