Can anyone help me out with these questions:

Given: Matrix(P)=

0-4-1

0 3 7

1 0 0

Such That: P-1AP=D is diagonal arranged so that the (1,1)-entry of D is different from the other diagonal entries.

Find an orthogonal matrix Q so that transpose(Q)AQ=D.

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2)

Given: matrix(A)=

-14/25 48/25 0

48/25 14/25 0

0 0 0

Find a diagonal matrix D and an orthogonal matrix Q so that the given matrix A = Q D transpose(Q).

Plz Help