Practice Problems

The matrix

A‾=[31−122−1220]\A=\begin{bmatrix} 3&1&-1\\ 2&2&-1\\ 2&2&0 \end{bmatrix}

has characteristic polynomial:

CA(x)=x3−5x2+8x−4=(x−1)(x−2)2C_{A}(x) = x^3 - 5x^2 + 8x - 4 = (x-1)(x-2)^2.

  1. Give the eigenvalues of A‾\A, then
  2. determine their algebraic and geometric multiplicity;
  3. finally,
  4. determine whether or not A‾\A is diagonalizable,
  5. and, if it is, give the matrices P ⁣‾ \matP and D ⁣‾ \D such that   ⁣A‾=P ⁣‾  D ⁣‾  P−1\ul{A} = \matP \, \D \, \minv{P} .

If λ1≤λ2≤λ3\lambda_1 \leq \lambda_2 \leq \lambda_3 (i.e. if we order the eigenvalues from the lowest value to highest value), then:
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