| Step | Hyp | Ref | Expression | 
						
							| 1 |  | kbfval | ⊢ ( ( 𝐴  ∈   ℋ  ∧  𝐵  ∈   ℋ )  →  ( 𝐴  ketbra  𝐵 )  =  ( 𝑥  ∈   ℋ  ↦  ( ( 𝑥  ·ih  𝐵 )  ·ℎ  𝐴 ) ) ) | 
						
							| 2 | 1 | fveq1d | ⊢ ( ( 𝐴  ∈   ℋ  ∧  𝐵  ∈   ℋ )  →  ( ( 𝐴  ketbra  𝐵 ) ‘ 𝐶 )  =  ( ( 𝑥  ∈   ℋ  ↦  ( ( 𝑥  ·ih  𝐵 )  ·ℎ  𝐴 ) ) ‘ 𝐶 ) ) | 
						
							| 3 |  | oveq1 | ⊢ ( 𝑥  =  𝐶  →  ( 𝑥  ·ih  𝐵 )  =  ( 𝐶  ·ih  𝐵 ) ) | 
						
							| 4 | 3 | oveq1d | ⊢ ( 𝑥  =  𝐶  →  ( ( 𝑥  ·ih  𝐵 )  ·ℎ  𝐴 )  =  ( ( 𝐶  ·ih  𝐵 )  ·ℎ  𝐴 ) ) | 
						
							| 5 |  | eqid | ⊢ ( 𝑥  ∈   ℋ  ↦  ( ( 𝑥  ·ih  𝐵 )  ·ℎ  𝐴 ) )  =  ( 𝑥  ∈   ℋ  ↦  ( ( 𝑥  ·ih  𝐵 )  ·ℎ  𝐴 ) ) | 
						
							| 6 |  | ovex | ⊢ ( ( 𝐶  ·ih  𝐵 )  ·ℎ  𝐴 )  ∈  V | 
						
							| 7 | 4 5 6 | fvmpt | ⊢ ( 𝐶  ∈   ℋ  →  ( ( 𝑥  ∈   ℋ  ↦  ( ( 𝑥  ·ih  𝐵 )  ·ℎ  𝐴 ) ) ‘ 𝐶 )  =  ( ( 𝐶  ·ih  𝐵 )  ·ℎ  𝐴 ) ) | 
						
							| 8 | 2 7 | sylan9eq | ⊢ ( ( ( 𝐴  ∈   ℋ  ∧  𝐵  ∈   ℋ )  ∧  𝐶  ∈   ℋ )  →  ( ( 𝐴  ketbra  𝐵 ) ‘ 𝐶 )  =  ( ( 𝐶  ·ih  𝐵 )  ·ℎ  𝐴 ) ) | 
						
							| 9 | 8 | 3impa | ⊢ ( ( 𝐴  ∈   ℋ  ∧  𝐵  ∈   ℋ  ∧  𝐶  ∈   ℋ )  →  ( ( 𝐴  ketbra  𝐵 ) ‘ 𝐶 )  =  ( ( 𝐶  ·ih  𝐵 )  ·ℎ  𝐴 ) ) |