how can i solve this polynomial equation?

clear all clc; syms x A=[x 2 1;1 0 -x;5 1 x]; det(A) r=solve('det(A)==0','x')

Answer 1

[Azzi Abdelmalek]

syms x
A=[x 2 1;1 0 -x;5 1 x]
r=double(solve(det(A),x))

[MA]

thanks