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lean_workbook_plus_16454

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

Alternatively, you can notice that the sum or product of an odd number of negatives is a negative. All squares must be non-negative. So we know (x−1)2(x-1)^2(x−1)2 is always positive (or zero, but that would make it false), so we only have to worry about (x−2)(x−3)\frac{(x-2)}{(x-3)}(x−3)(x−2)​ . x−2x-2x−2 is positive if x>2x>2x>2 and negative if x<2x<2x<2 , and x−3x-3x−3 is positive if x>3x>3x>3 and negative if x<3x<3x<3 . We want one of them will be positive and the other will be negative to get a negative quotient. This happens if 2<x<32<x<32<x<3 , or (2,3)\boxed{(2,3)}(2,3)​ .

Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_16454  (x : ℝ)
  (h₀ : 0 < (x - 1)^2)
  (h₁ : (x - 2) / (x - 3) < 0) :
  2 < x ∧ x < 3   :=  by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook

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