lean_workbook_plus_9918

Proved

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

Prove the rule: $\frac{x}{y}<\frac{x+a}{y+a}$ where $a>0, x>0, y>0$ and $x<y$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_9918 (x y a : ℝ) (ha : 0 < a) (hx : 0 < x) (hy : 0 < y) (hxy : x < y) : x / y < (x + a) / (y + a)   :=  by sorry

Source