7

I have the following variables

```
Σ = {{64, 40.8, 80}, {40.8, 289, 238}, {80, 238, 400}};
μ = {{9}, {12}, {15}};
ι = {{1}, {1}, {1}};
```

And then I define the following matrix:

```
A = {{Transpose[μ].Inverse[Σ].μ,
Transpose[μ].Inverse[Σ].ι}, {Transpose[μ].Inverse[Σ].ι,
Transpose[ι].Inverse[Σ].ι}};
```

Which gives me the matrix:

Now when I try to get the determinant of the matrix i get an error:

Any1 know what the problem is?

`Det`

will take the determinant of a symbolic matrix, so you could also use something like`Det[A] /. {\[CapitalSigma] -> {{64, 40.8, 80}, {40.8, 289, 238}, {80, 238, 400}}, \[Mu] -> {9, 12, 15}, \[Iota] -> {1, 1, 1}}`

with A as defined below by Bob Hanlon (https://mathematica.stackexchange.com/a/148259/106) – user1066 – 2017-06-13T14:34:19.483