>> a=sym('[x,x^2,x^3;1,2*x,3*x^3;4,2,6*x]')
a =
[ x,x^2,x^3]
[ 1,2*x,3*x^3]
[ 4,2,6*x]
>> det(a)
ans =
12*x^5 - 14*x^4 + 8*x^3
>>