The degree of zero polynomial is undefined.
Before proceeding further, keep it in mind that: “The degree of the polynomial is the highest power of its variable.”
Other constant Polynomials have degree =0.
Why is it so?
Take for example P(x) = 2.
It can be written as P(x)=2x0.
P(x)=100 can be written as 100x0.
The power of variables is 0. So the degree is 0 in each case. It can’t be written as 100x1 or 100x2 because the polynomial itself will change as its value and degree will change.
But p(x)=0 can be written as 0x0 or 0x1, or 0x2 or 0x3 and so on. It is so because 0 multiplied by any number will give zero itself as an answer.
Now you can see that its degree can be considered as 0,1,2,3 or any other non-negative integer.
Which one to take and which one to reject?
This is the reason, the degree of zero polynomial is undefined.