I'm used to seeing rings represented as sets, but in one of my homework problems, I am asked to:
Find the number of zero-divisors of $R_{x^2-x}$.
Can somebody please explain what this notation actually means, as I've never seen it before? If the context of the question is required, previous questions have been about the subring $R = \{ax^2+bx+c \mid a \in 4\mathbb{Z}_8, b \in 2\mathbb{Z}_8, c \in \mathbb{Z}_8\}$ of $\mathbb{Z}_8[x]$.
Thanks in advance!