Is -5 a polynomial?

[hockeyquinn25]

If not, is it because the degree is 0 or is it because the leading coefficient is 0?

 

[Ishuda]

If not, is it because the degree is 0 or is it because the leading coefficient is 0?

Technically
a_n xⁿ + a_n-1 x^n-1 + ... + a₁ x + a₀
is a polynomial for all sets of {a_j, j = 0, 1, 2, 3, ..., n} and n \(\displaystyle \ge\) 0. The degree of the polynomial is the maximum of j such that a_j \(\displaystyle \ne\) 0 [or, to be complete, if that j doesn't exist, the degree is zero]. So, yes, -5 is a polynomial of degree 0.