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Find matrix A given eigenvector and eigenvalue.?

Given that the matrix A has eigenvalues L1 = 8 with corresponding eigenvector v1 =(1,-3) L2=4 with corresponding eigenvector v2 =(-1,4), find A

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  • Hosam
    Lv 6
    8 years ago

    A P = P D

    i.e. A = P D P^-1

    where P is the matrix of eigenvectors, and D is the diagonal matrix of eigenvalues.

    D = [ 8, 0; 0, 4 ]

    P = [1, -1; -3, 4 ]

    All we have to do is find P^-1.

    | P | = 1, So P^-1 = [ 4, 1; 3, 1 ]

    Finally A = P D P^-1 = [1, -1; -3, 4] [ 8, 0; 0, 4] [4, 1; 3, 1]

    = [8, -4; -24, 16] [4, 1; 3, 1]

    = [20, 4; -48, -8]

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