Find Ratio ||v||/||u|| for u and v

[Whiz]

Homework Statement

For u = (−1, 2, 1) and v = (3, 3, 6) find the ratio ||v|| / ||u||

Homework Equations

|| u || = (u^2 + u2^2 + ...un^2)^.5

The Attempt at a Solution

I found the || u || to be 6^(1/2) and || v || to be 54^(1/2)
Therefore the ratio should be 54^(1/2) divided by 6^(1/2), which calculates to 3. It turns out the answer is incorrect. Can anyone show me where I went wrong?

Thanks.

 

[LCKurtz]

Nowhere.

 

[Mark44]

I agree. The ratio is 3.

$$\frac{\sqrt{54}}{\sqrt{6}}~=~\frac{3\sqrt{6}}{\sqrt{6}}=~3$$

 

[Whiz]

Okay thanks. I'll have to tell my instructor about it.

 

[Mark44]

Before you do, make sure that the problem you posted here is exactly the same as in your book or wherever this problem came from.