Determin if x is an eigenvector of (5I-A). What is the corresponding eigenvalue Solution ?=5 ? is an eigenvalue of \"-A ? Av = ?v for some v ? 0 (definition of eigenvalue) ? (-A + ?I)x = 0 has x = v as a nontrivial solution ? -A + ?I is not invertible (invertibility criterion for square matrices) ? det(-A + ?I) = 0. Step 1: Solve the characteristic equation det(-A + ?I) = 0 and get the eigenvalues ?1, ?2, ... . Step 2: For each eigenvalue ?i, solve the homogeneuous system (-A + ?iI)x = 0 and get the eigenvectors with ?i as the eigenvalue. In the second step, the answer is actually presented as a basis of nul(-A +?iI), called the eigenspace of A with eigenvalue ?i.