The eigen values of the matrix \[\left[ {\begin{array}{*{20}{c}} 4&{ – 2} \\ { – 2}&1 \end{array}} \right]\] A. are 1 and 4 B. are -1 and 2 C. are 0 and 5 D. cannot be determined

are 1 and 4
are -1 and 2
are 0 and 5
cannot be determined

The correct answer is A.

The eigenvalues of a matrix are the roots of its characteristic polynomial. The characteristic polynomial of a matrix $A$ is given by $$p(x) = |xI – A|.$$

In this case, we have $$p(x) = |xI – \left[ {\begin{array}{*{20}{c}} 4&{ – 2} \ { – 2}&1 \end{array}} \right]| = |x – 4| |x – 1| = (x – 4)(x – 1).$$

Therefore, the eigenvalues of the matrix are $4$ and $1$.

Option B is incorrect because the eigenvalues are not $-1$ and $2$. Option C is incorrect because the eigenvalues are not $0$ and $5$. Option D is incorrect because the eigenvalues can be determined.

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