Finding missing array value of a singular matrix

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?

Answer 1

[Stephen23]

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

[Ollie]

Thank you very much