diff --git a/Math2001/Homework/hw7.lean b/Math2001/Homework/hw7.lean new file mode 100644 index 00000000..5d6fb4ff --- /dev/null +++ b/Math2001/Homework/hw7.lean @@ -0,0 +1,43 @@ +/- Copyright (c) Heather Macbeth, 2023. All rights reserved. -/ +import Mathlib.Data.Real.Basic +import Library.Basic +import Library.Tactic.ModEq +import AutograderLib + +math2001_init + + +/-! # Homework 7 + +Don't forget to compare with the text version, +https://github.com/hrmacbeth/math2001/wiki/Homework-7, +for clearer statements and any special instructions. -/ + + +@[autograded 5] +theorem problem1 (P Q : Prop) : ¬ (P → Q) ↔ (P ∧ ¬ Q) := by + sorry + +@[autograded 3] +theorem problem2 : ¬ (∀ x : ℚ, 2 * x ^ 2 ≥ x) := by + push_neg + sorry + +@[autograded 4] +theorem problem3 (n : ℕ) : 6 ^ n ≡ 1 [ZMOD 7] ∨ 6 ^ n ≡ 6 [ZMOD 7] := by + sorry + +@[autograded 4] +theorem problem4 (n : ℕ) : + 4 ^ n ≡ 1 [ZMOD 7] ∨ 4 ^ n ≡ 2 [ZMOD 7] ∨ 4 ^ n ≡ 4 [ZMOD 7] := by + sorry + +@[autograded 5] +theorem problem5 {a : ℝ} (ha : -1 ≤ a) : ¬ ∃ n : ℕ, (1 + a) ^ n < 1 + n * a := by + push_neg + sorry + +@[autograded 4] +theorem problem6 : forall_sufficiently_large n : ℕ, (3:ℤ) ^ n ≥ 2 ^ n + 100 := by + dsimp + sorry