Vectors are parallel

[tarheels88]

Homework Statement

Given vectors b and c are they parallel? If so find such scalar s that c=sb, otherwise write N for no.

a) b=<0,3,4>, c=<0,6,-8)

b) b=<10,6>, c=<-15,-9>

Homework Equations

c=sb is a property of the dot product.

The Attempt at a Solution

For a) I put No because <0,6,-8> does not = <0s, 3s, 4s> because S=2
For b) I put Yes because S=-3/2 which would give you both outcomes of the vectors

Am I correct?

 

[Dick]

Yes, you are. If you'd explain why you need to pick s=2 in the first case, that would probably help. "because s=2" isn't much of an explanation.

 

[tarheels88]

I put s=2 because I was finding a multiple of the two vectors given. Then I calculate 3s=6, that would then calculate to c=2.

 

[Dick]

I put s=2 because I was finding a multiple of the two vectors given. Then I calculate 3s=6, that would then calculate to c=2.

Right, so the only possibility is s=2, and since that doesn't work there is no s that works. I knew you knew that. Just wanted you to add that if you are turning this in as a homework exercise.