Question

how to find an unknown in matrix A if it is invertible

Answer 1

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Answer 2

what's the matrix? :)

Answer 3

1-m 1 -1
2 1-m 2
2 -1 4-m

Answer 4

If a matrix is invertible, its determinant cannot be 0. Try to express its determinant :)

Answer 5

this is the only data given

Answer 6

sorry I don't know how to do

Answer 7

if it is invertible then find its determinant and equate to 0 .. find the value of eigenvalues n.. and put the that values of n one after another .. u will get matrices for different values of n