Matrix Calculation in MATLAB

Could someone help me solve this problem in Matlab.. Suppose I have this Matriks

    A=[2-x 5    
       2   3-x ]

So, it can be written as : (to alculate the determinant)

   (2-x * 3-x)-(5*2)=0

But In matlab if I cannot put x before I define it..

There will be an error :

    Undefined function or variable 'x'.

Please help me!! How to be able multiply (2-x * 3-x) ?????

I'm not allowed to use det function from Matlab!!!

Answer 1

[Mischa Kim]

Tanya, use symbolic math:

 syms x
 A = (2-x)*(3-x)
 A =
(x - 2)*(x - 3)

or, to solve your problem

 A = (2-x)*(3-x) - (5*2);
 solve(A)
 ans =
 41^(1/2)/2 + 5/2
 5/2 - 41^(1/2)/2

Answer 2

[Paul]

Define x as symbolic variable. Also (2-x * 3-x) should be ((2-x) * (3-x)) else you are calculating (2- (x * 3) -x). So:

   syms x
   ((2-x) * (3-x))-(5*2)

If you want to calculate the values for which the determinant is 0:

   x0=solve(((2-x) * (3-x))-(5*2)==0)
   double(x0)