# Math Help - Vectors - parallel?

1. ## Vectors - parallel?

How can I tell if these two vectors are parallel?

u = <3,5>
v = <-2, 1>

Thanks for any help!

2. Originally Posted by live_laugh_luv27
How can I tell if these two vectors are parallel?

u = <3,5>
v = <-2, 1>

Thanks for any help!
Two vectors are parallel if and only if one is a multiple of the other.

3. Two vectors are parallel if they are non-zero multiples of each other.

4. Ok..how would I know if they are multiples of one another?

5. u = <3,5>
v = <-2, 1>

if two vectors are parrallel, then:

u= kv, where k is some constant.

<3,5>= k<-2,1>

for values of x:
3= -2k

k= -3/2

for values of y:
5= (1)k

since k for x does not equal to k for y, the two vectors are not parrallel.

note: you could also use a dot product to check this

6. great, thanks for explaining!