have := isLittleO_log_rpow_atTop (r := -r / 2) (by linarith) |>.isBigO
case ho
r : ℝ
rneg : r < 0
N : ℕ
Npos : 0 < N
⊢ (fun x => |x ^ (r - 1)| * |x.log|) =O[atTop] fun x => x ^ (r / 2 - 1)
case ho
r : ℝ
rneg : r < 0
N : ℕ
Npos : 0 < N
this : Real.log =O[atTop] fun x => x ^ (-r / 2)
⊢ (fun x => |x ^ (r - 1)| * |x.log|) =O[atTop] fun x => x ^ (r / 2 - 1)