lean_workbook_plus_61241

Proved

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

If $a,b,c,d\in[0,1]$ then show that: $3(a+b+c+d)\le8+(a^3+b^3+c^3+d^3)$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_61241 (a b c d : ℝ) (ha : 0 ≤ a ∧ a ≤ 1) (hb : 0 ≤ b ∧ b ≤ 1) (hc : 0 ≤ c ∧ c ≤ 1) (hd : 0 ≤ d ∧ d ≤ 1): 3 * (a + b + c + d) ≤ 8 + a^3 + b^3 + c^3 + d^3   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook

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