Theorem: Real.geom_mean_weighted_of_constant
File: Mathlib/Analysis/MeanInequalities.lean

tactic: refine prod_congr rfl fun i hi => ?_
state_before: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
⊢ ∏ i ∈ s, z i ^ w i = ∏ i ∈ s, x ^ w i
state_after: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
i : ι
hi : i ∈ s
⊢ z i ^ w i = x ^ w i

tactic: rcases eq_or_ne (w i) 0 with h₀ | h₀
state_before: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
i : ι
hi : i ∈ s
⊢ z i ^ w i = x ^ w i
state_after: case inl
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
i : ι
hi : i ∈ s
h₀ : w i = 0
⊢ z i ^ w i = x ^ w i

case inr
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
i : ι
hi : i ∈ s
h₀ : w i ≠ 0
⊢ z i ^ w i = x ^ w i

tactic: rw [h₀, rpow_zero, rpow_zero]
state_before: case inl
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
i : ι
hi : i ∈ s
h₀ : w i = 0
⊢ z i ^ w i = x ^ w i
state_after: no goals

tactic: rw [hx i hi h₀]
state_before: case inr
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
i : ι
hi : i ∈ s
h₀ : w i ≠ 0
⊢ z i ^ w i = x ^ w i
state_after: no goals

tactic: rw [← rpow_sum_of_nonneg _ hw, hw', rpow_one]
state_before: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
⊢ ∏ i ∈ s, x ^ w i = x
state_after: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
⊢ 0 ≤ x

tactic: have : (∑ i ∈ s, w i) ≠ 0 := by
  rw [hw']
  exact one_ne_zero
state_before: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
⊢ 0 ≤ x
state_after: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
this : ∑ i ∈ s, w i ≠ 0
⊢ 0 ≤ x

tactic: obtain ⟨i, his, hi⟩ := exists_ne_zero_of_sum_ne_zero this
state_before: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
this : ∑ i ∈ s, w i ≠ 0
⊢ 0 ≤ x
state_after: case intro.intro
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
this : ∑ i ∈ s, w i ≠ 0
i : ι
his : i ∈ s
hi : w i ≠ 0
⊢ 0 ≤ x

tactic: rw [← hx i his hi]
state_before: case intro.intro
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
this : ∑ i ∈ s, w i ≠ 0
i : ι
his : i ∈ s
hi : w i ≠ 0
⊢ 0 ≤ x
state_after: case intro.intro
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
this : ∑ i ∈ s, w i ≠ 0
i : ι
his : i ∈ s
hi : w i ≠ 0
⊢ 0 ≤ z i

tactic: exact hz i his
state_before: case intro.intro
ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
this : ∑ i ∈ s, w i ≠ 0
i : ι
his : i ∈ s
hi : w i ≠ 0
⊢ 0 ≤ z i
state_after: no goals

tactic: rw [hw']
state_before: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
⊢ ∑ i ∈ s, w i ≠ 0
state_after: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
⊢ 1 ≠ 0

tactic: exact one_ne_zero
state_before: ι : Type u
s : Finset ι
w z : ι → ℝ
x : ℝ
hw : ∀ i ∈ s, 0 ≤ w i
hw' : ∑ i ∈ s, w i = 1
hz : ∀ i ∈ s, 0 ≤ z i
hx : ∀ i ∈ s, w i ≠ 0 → z i = x
⊢ 1 ≠ 0
state_after: no goals