Solution
= Solution
The relation is reflexive and symmetric, but not transitive. For example,
$$
1\sim0,qquad0\sim-1,
$$
while $1\not\sim-1$. Hence it is not an equivalence relation.
= Solution
The relation is reflexive and symmetric, but not transitive. For example,
$$
1\sim0,qquad0\sim-1,
$$
while $1\not\sim-1$. Hence it is not an equivalence relation.