rw [mul_div_assoc, mul_assoc]
case neg
ψ : ℝ → ℝ
diffΨ : ContDiff ℝ 1 ψ
ψpos : ∀ (x : ℝ), 0 ≤ ψ x
suppΨ : support ψ ⊆ Icc (1 / 2) 2
mass_one : ∫ (x : ℝ) in Ioi 0, ψ x / x = 1
X : ℝ
X_pos : 0 < X
ε : ℝ
εpos : 0 < ε
n : ℕ
t : ℝ
n_ne_zero : ¬n = 0
⊢ ↑(Λ n) * mellin (fun x => ↑(Smooth1 ψ ε x)) (2 + ↑t * I) * ↑X ^ (2 + ↑t * I) / ↑n ^ (2 + ↑t * I) =
    ↑(Λ n) * (mellin (fun x => ↑(Smooth1 ψ ε x)) (2 + ↑t * I) * (↑X / ↑n) ^ (2 + ↑t * I))
case neg
ψ : ℝ → ℝ
diffΨ : ContDiff ℝ 1 ψ
ψpos : ∀ (x : ℝ), 0 ≤ ψ x
suppΨ : support ψ ⊆ Icc (1 / 2) 2
mass_one : ∫ (x : ℝ) in Ioi 0, ψ x / x = 1
X : ℝ
X_pos : 0 < X
ε : ℝ
εpos : 0 < ε
n : ℕ
t : ℝ
n_ne_zero : ¬n = 0
⊢ ↑(Λ n) * (mellin (fun x => ↑(Smooth1 ψ ε x)) (2 + ↑t * I) * (↑X ^ (2 + ↑t * I) / ↑n ^ (2 + ↑t * I))) =
    ↑(Λ n) * (mellin (fun x => ↑(Smooth1 ψ ε x)) (2 + ↑t * I) * (↑X / ↑n) ^ (2 + ↑t * I))