α : Type u_1
inst✝² : AddGroup α
inst✝¹ : LinearOrder α
inst✝ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
a✝ b c a : α
⊢ a + -a ≤ a + abs a
α : Type u_1
inst✝² : AddGroup α
inst✝¹ : LinearOrder α
inst✝ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
a✝ b c a : α
⊢ 0 ≤ a + abs a
rw [← add_right_neg a]
case bc
α : Type u_1
inst✝² : AddGroup α
inst✝¹ : LinearOrder α
inst✝ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
a✝ b c a : α
⊢ -a ≤ abs a
α : Type u_1
inst✝² : AddGroup α
inst✝¹ : LinearOrder α
inst✝ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
a✝ b c a : α
⊢ a + -a ≤ a + abs a
apply add_le_add_left
no goals
case bc
α : Type u_1
inst✝² : AddGroup α
inst✝¹ : LinearOrder α
inst✝ : CovariantClass α α (fun x x_1 => x + x_1) fun x x_1 => x ≤ x_1
a✝ b c a : α
⊢ -a ≤ abs a
exact neg_le_abs_self a