a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
⊢ 1 < (a ^ b - 1) / (a - 1)
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
⊢ 2 ≤ (a ^ b - 1) / (a - 1)
change 1 < _
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
h₁ : a - 1 ∣ a ^ b - 1
⊢ 1 < (a ^ b - 1) / (a - 1)
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
⊢ 1 < (a ^ b - 1) / (a - 1)
have h₁ : a - 1 ∣ a ^ b - 1 := by simpa only [one_pow] using nat_sub_dvd_pow_sub_pow a 1 b
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
h₁ : a - 1 ∣ a ^ b - 1
⊢ a < a ^ b
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
h₁ : a - 1 ∣ a ^ b - 1
⊢ 1 < (a ^ b - 1) / (a - 1)
rw [Nat.lt_div_iff_mul_lt h₁, mul_one, tsub_lt_tsub_iff_right (Nat.le_of_succ_le ha)]
case h.e'_3
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
h₁ : a - 1 ∣ a ^ b - 1
⊢ a = a ^ 1
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
h₁ : a - 1 ∣ a ^ b - 1
⊢ a < a ^ b
convert pow_lt_pow (Nat.lt_of_succ_le ha) hb
no goals
case h.e'_3
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
h₁ : a - 1 ∣ a ^ b - 1
⊢ a = a ^ 1
rw [pow_one]
no goals
a b : ℕ
ha : 2 ≤ a
hb : 2 ≤ b
⊢ a - 1 ∣ a ^ b - 1
simpa only [one_pow] using nat_sub_dvd_pow_sub_pow a 1 b