α : Type u_1
inst✝ : OrderedAddCommGroup α
a b c : α
this : ∀ (a_1 : Set α), ((fun x => a + x) ∘ fun x => -x) '' a_1 = (fun x => a + x) '' ((fun x => -x) '' a_1)
⊢ (fun x => a - x) '' Ioc b c = Ico (a - c) (a - b)
α : Type u_1
inst✝ : OrderedAddCommGroup α
a b c : α
⊢ (fun x => a - x) '' Ioc b c = Ico (a - c) (a - b)
have := image_comp (fun x => a + x) fun x => -x
α : Type u_1
inst✝ : OrderedAddCommGroup α
a b c : α
this : ∀ (a_1 : Set α), (fun x => a + -x) '' a_1 = (fun x => a + x) '' ((fun x => -x) '' a_1)
⊢ (fun x => a - x) '' Ioc b c = Ico (a - c) (a - b)
α : Type u_1
inst✝ : OrderedAddCommGroup α
a b c : α
this : ∀ (a_1 : Set α), ((fun x => a + x) ∘ fun x => -x) '' a_1 = (fun x => a + x) '' ((fun x => -x) '' a_1)
⊢ (fun x => a - x) '' Ioc b c = Ico (a - c) (a - b)
dsimp [Function.comp] at this
no goals
α : Type u_1
inst✝ : OrderedAddCommGroup α
a b c : α
this : ∀ (a_1 : Set α), (fun x => a + -x) '' a_1 = (fun x => a + x) '' ((fun x => -x) '' a_1)
⊢ (fun x => a - x) '' Ioc b c = Ico (a - c) (a - b)
simp [sub_eq_add_neg, this, add_comm]