1. x : ℝ
2. r0 < (r1 + -(x * x))
⊢ |x| < r1
{ ((Assert (r1 + -(x * x)) = ((r1 + x) * (r1 - x)) BY (nRNorm 0 THEN Auto)) THEN (RWO "-1" (-2) THENA Auto)) }
2. r0 < ((r1 + x) * (r1 - x))
3. (r1 + -(x * x)) = ((r1 + x) * (r1 - x))