The matrix \[\left( {\begin{array}{*{20}{c}} 2&{ – 4} \\ 4&{ – 2} \end{array}} \right)\] has A. real eigenvalues and eigenvectors B. real eigenvalues but complex eigenvectors C. complex eigenvalues but real eigenvectors D. complex eigenvalues and eigenvectors

real eigenvalues and eigenvectors
real eigenvalues but complex eigenvectors
complex eigenvalues but real eigenvectors
complex eigenvalues and eigenvectors

The correct answer is $\boxed{\text{(B) real eigenvalues but complex eigenvectors}}$.

To find the eigenvalues and eigenvectors of a matrix, we can use the following formula:

$$\lambda v = A v$$

where $\lambda$ is the eigenvalue, $v$ is the eigenvector, and $A$ is the matrix.

In this case, we have the following matrix:

$$A = \left( {\begin{array}{*{20}{c}} 2&{ – 4} \ 4&{ – 2} \end{array}} \right)$$

Substituting this into the formula, we get the following equations:

$$\begin{align}
2 v_1 – 4 v_2 &= \lambda v_1 \
4 v_1 – 2 v_2 &= \lambda v_2
\end{align
}$$

Solving these equations, we get the following eigenvalues:

$$\lambda = 2 \pm 2 i$$

and the following eigenvectors:

$$v_1 = \left( {\begin{array}{c} 1 \ -i \end{array}} \right) \text{ and } v_2 = \left( {\begin{array}{c} 1 \ i \end{array}} \right)$$

As you can see, the eigenvalues are real, but the eigenvectors are complex. This is because the matrix $A$ is not a real matrix. It is a complex matrix.

Therefore, the correct answer is $\boxed{\text{(B) real eigenvalues but complex eigenvectors}}$.