However, the symbol-string is not justified: although fT (T ) does connote substitut- ing the endomorphism T for the indeterminate x, the substitution does not imply taking the determinant of 0. One way to understand the substitution is first to
expand the polynomial det(x • 1V − T ) and only then replace x by T . For example, if n = 2 and we choose a basis of V then T acquires a matrix I a b l, and