MATLAB: Finding missing array value of a singular matrix

arraycondition numberdeterminantinverseMATLABmatrixranksingular

How do I use matlab to find the value of x that makes the matrix A = [2,5,7;-2,3,-4;1,5,x] singular ie has determinant zero?

Best Answer

A simple numerical solution using fzero:
>> fun = @(x)det([2,5,7;-2,3,-4;1,5,x]);
>> x = fzero(fun,0.1)
x =
       4.4375
>> fun(x)
ans =
     0
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