Determine whether [tex]\( u \)[/tex] and [tex]\( v \)[/tex] are orthogonal, parallel, or neither.

[tex]\[ u = -4i, \; v = i \][/tex]

Answer:
A. Orthogonal
B. Parallel
C. Neither



Answer :

To determine the relationship between the vectors [tex]\(u = -4i\)[/tex] and [tex]\(v = i\)[/tex], we need to consider their dot product and their direction. We will assess whether these vectors are orthogonal, parallel, or neither.

1. Dot Product:

The dot product of two complex vectors [tex]\(u\)[/tex] and [tex]\(v\)[/tex] is given by [tex]\(\langle u, v \rangle = \text{Re}(u \cdot \overline{v})\)[/tex].

Here, [tex]\(u = -4i\)[/tex] and [tex]\(v = i\)[/tex]. We need to compute the complex conjugate of [tex]\(v\)[/tex], which is [tex]\(\overline{v} = -i\)[/tex].

The dot product is then calculated as:
[tex]\[ \langle u, v \rangle = (-4i) \cdot (-i) \][/tex]

We simplify this product:
[tex]\[ (-4i) \cdot (-i) = 4 \][/tex]

Thus, the real part of the dot product is:
[tex]\[ \text{Re}(4) = 4 \][/tex]

Since the dot product is non-zero (4), the vectors [tex]\(u\)[/tex] and [tex]\(v\)[/tex] are not orthogonal. Orthogonality requires the dot product to be zero.

2. Parallelism:

To determine if the vectors [tex]\(u\)[/tex] and [tex]\(v\)[/tex] are parallel, we need to check if one is a scalar multiple of the other.

We have [tex]\(u = -4i\)[/tex] and [tex]\(v = i\)[/tex].

We can write:
[tex]\[ u = (-4) \cdot v \][/tex]

Since [tex]\(u\)[/tex] is indeed a scalar multiple of [tex]\(v\)[/tex] (with the scalar being [tex]\(-4\)[/tex]), the vectors [tex]\(u\)[/tex] and [tex]\(v\)[/tex] are parallel.

Therefore, the vectors [tex]\(u\)[/tex] and [tex]\(v\)[/tex] are parallel. The final answer is:

[tex]\[ \boxed{\text{Parallel}} \][/tex]