Trying to find the value of z for any value of k

I have the following code:

syms k
A = [1 -((k^2)+3) ((k^2)+3) -1];
Y = roots(A)

which returns:

Y =                                           1
k^2/2 - (k*(k^2 + 4)^(1/2))/2 + 1
(k*(k^2 + 4)^(1/2))/2 + k^2/2 + 1

now, I have:

Z = Y(3,1)*Y(2,1)

which returns:

Z =
(k^2/2 - (k*(k^2 + 4)^(1/2))/2 + 1)*((k*(k^2 + 4)^(1/2))/2 + k^2/2 + 1)

Now, I want to test multiple values of k in the function Z, how do I do this?

Answer 1

[KSSV]

Read about subs. Using this, you can substitute the required value of k. You need to convert the result/ syms call into a number using double.

double(subs(Z,k,1))