Question

If u is <1,5> find ||u||

A.4
B.6
C. Square root 6
D. Square root 26

Answer 1

I think it would be D

Answer 2

u = <1,5> is a vector in the form <a,b> with a = 1 and b = 5.

||u|| = sqrt(a^2+b^2) is the magnitude or length of the vector

||u|| = sqrt(1^2+5^2)

||u| = sqrt(26)

The answer is choice D

Check out the attached image below for a visual.