| Step | Hyp | Ref | Expression | 
						
							| 1 |  | simpl2l |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> A e. ( EE ` N ) ) | 
						
							| 2 |  | fveecn |  |-  ( ( A e. ( EE ` N ) /\ j e. ( 1 ... N ) ) -> ( A ` j ) e. CC ) | 
						
							| 3 | 1 2 | sylancom |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> ( A ` j ) e. CC ) | 
						
							| 4 |  | simpl2r |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> C e. ( EE ` N ) ) | 
						
							| 5 |  | fveecn |  |-  ( ( C e. ( EE ` N ) /\ j e. ( 1 ... N ) ) -> ( C ` j ) e. CC ) | 
						
							| 6 | 4 5 | sylancom |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> ( C ` j ) e. CC ) | 
						
							| 7 |  | elicc01 |  |-  ( T e. ( 0 [,] 1 ) <-> ( T e. RR /\ 0 <_ T /\ T <_ 1 ) ) | 
						
							| 8 | 7 | simp1bi |  |-  ( T e. ( 0 [,] 1 ) -> T e. RR ) | 
						
							| 9 | 8 | adantr |  |-  ( ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) -> T e. RR ) | 
						
							| 10 | 9 | 3ad2ant3 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) -> T e. RR ) | 
						
							| 11 | 10 | recnd |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) -> T e. CC ) | 
						
							| 12 | 11 | adantr |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> T e. CC ) | 
						
							| 13 |  | fveq2 |  |-  ( i = j -> ( B ` i ) = ( B ` j ) ) | 
						
							| 14 |  | fveq2 |  |-  ( i = j -> ( A ` i ) = ( A ` j ) ) | 
						
							| 15 | 14 | oveq2d |  |-  ( i = j -> ( ( 1 - T ) x. ( A ` i ) ) = ( ( 1 - T ) x. ( A ` j ) ) ) | 
						
							| 16 |  | fveq2 |  |-  ( i = j -> ( C ` i ) = ( C ` j ) ) | 
						
							| 17 | 16 | oveq2d |  |-  ( i = j -> ( T x. ( C ` i ) ) = ( T x. ( C ` j ) ) ) | 
						
							| 18 | 15 17 | oveq12d |  |-  ( i = j -> ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) | 
						
							| 19 | 13 18 | eqeq12d |  |-  ( i = j -> ( ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) <-> ( B ` j ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) ) | 
						
							| 20 | 19 | rspccva |  |-  ( ( A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) /\ j e. ( 1 ... N ) ) -> ( B ` j ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) | 
						
							| 21 | 20 | adantll |  |-  ( ( ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) /\ j e. ( 1 ... N ) ) -> ( B ` j ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) | 
						
							| 22 | 21 | 3ad2antl3 |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> ( B ` j ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) | 
						
							| 23 |  | oveq2 |  |-  ( ( B ` j ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) -> ( ( A ` j ) - ( B ` j ) ) = ( ( A ` j ) - ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) ) | 
						
							| 24 | 23 | oveq1d |  |-  ( ( B ` j ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) -> ( ( ( A ` j ) - ( B ` j ) ) ^ 2 ) = ( ( ( A ` j ) - ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) ^ 2 ) ) | 
						
							| 25 |  | subdi |  |-  ( ( T e. CC /\ ( A ` j ) e. CC /\ ( C ` j ) e. CC ) -> ( T x. ( ( A ` j ) - ( C ` j ) ) ) = ( ( T x. ( A ` j ) ) - ( T x. ( C ` j ) ) ) ) | 
						
							| 26 | 25 | 3coml |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( T x. ( ( A ` j ) - ( C ` j ) ) ) = ( ( T x. ( A ` j ) ) - ( T x. ( C ` j ) ) ) ) | 
						
							| 27 |  | ax-1cn |  |-  1 e. CC | 
						
							| 28 |  | subcl |  |-  ( ( 1 e. CC /\ T e. CC ) -> ( 1 - T ) e. CC ) | 
						
							| 29 | 27 28 | mpan |  |-  ( T e. CC -> ( 1 - T ) e. CC ) | 
						
							| 30 | 29 | adantl |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( 1 - T ) e. CC ) | 
						
							| 31 |  | simpl |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( A ` j ) e. CC ) | 
						
							| 32 |  | subdir |  |-  ( ( 1 e. CC /\ ( 1 - T ) e. CC /\ ( A ` j ) e. CC ) -> ( ( 1 - ( 1 - T ) ) x. ( A ` j ) ) = ( ( 1 x. ( A ` j ) ) - ( ( 1 - T ) x. ( A ` j ) ) ) ) | 
						
							| 33 | 27 30 31 32 | mp3an2i |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( ( 1 - ( 1 - T ) ) x. ( A ` j ) ) = ( ( 1 x. ( A ` j ) ) - ( ( 1 - T ) x. ( A ` j ) ) ) ) | 
						
							| 34 |  | nncan |  |-  ( ( 1 e. CC /\ T e. CC ) -> ( 1 - ( 1 - T ) ) = T ) | 
						
							| 35 | 27 34 | mpan |  |-  ( T e. CC -> ( 1 - ( 1 - T ) ) = T ) | 
						
							| 36 | 35 | oveq1d |  |-  ( T e. CC -> ( ( 1 - ( 1 - T ) ) x. ( A ` j ) ) = ( T x. ( A ` j ) ) ) | 
						
							| 37 | 36 | adantl |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( ( 1 - ( 1 - T ) ) x. ( A ` j ) ) = ( T x. ( A ` j ) ) ) | 
						
							| 38 |  | mullid |  |-  ( ( A ` j ) e. CC -> ( 1 x. ( A ` j ) ) = ( A ` j ) ) | 
						
							| 39 | 38 | oveq1d |  |-  ( ( A ` j ) e. CC -> ( ( 1 x. ( A ` j ) ) - ( ( 1 - T ) x. ( A ` j ) ) ) = ( ( A ` j ) - ( ( 1 - T ) x. ( A ` j ) ) ) ) | 
						
							| 40 | 39 | adantr |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( ( 1 x. ( A ` j ) ) - ( ( 1 - T ) x. ( A ` j ) ) ) = ( ( A ` j ) - ( ( 1 - T ) x. ( A ` j ) ) ) ) | 
						
							| 41 | 33 37 40 | 3eqtr3rd |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( ( A ` j ) - ( ( 1 - T ) x. ( A ` j ) ) ) = ( T x. ( A ` j ) ) ) | 
						
							| 42 | 41 | oveq1d |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( ( ( A ` j ) - ( ( 1 - T ) x. ( A ` j ) ) ) - ( T x. ( C ` j ) ) ) = ( ( T x. ( A ` j ) ) - ( T x. ( C ` j ) ) ) ) | 
						
							| 43 | 42 | 3adant2 |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( ( A ` j ) - ( ( 1 - T ) x. ( A ` j ) ) ) - ( T x. ( C ` j ) ) ) = ( ( T x. ( A ` j ) ) - ( T x. ( C ` j ) ) ) ) | 
						
							| 44 |  | simp1 |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( A ` j ) e. CC ) | 
						
							| 45 |  | mulcl |  |-  ( ( ( 1 - T ) e. CC /\ ( A ` j ) e. CC ) -> ( ( 1 - T ) x. ( A ` j ) ) e. CC ) | 
						
							| 46 | 29 45 | sylan |  |-  ( ( T e. CC /\ ( A ` j ) e. CC ) -> ( ( 1 - T ) x. ( A ` j ) ) e. CC ) | 
						
							| 47 | 46 | ancoms |  |-  ( ( ( A ` j ) e. CC /\ T e. CC ) -> ( ( 1 - T ) x. ( A ` j ) ) e. CC ) | 
						
							| 48 | 47 | 3adant2 |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( 1 - T ) x. ( A ` j ) ) e. CC ) | 
						
							| 49 |  | mulcl |  |-  ( ( T e. CC /\ ( C ` j ) e. CC ) -> ( T x. ( C ` j ) ) e. CC ) | 
						
							| 50 | 49 | ancoms |  |-  ( ( ( C ` j ) e. CC /\ T e. CC ) -> ( T x. ( C ` j ) ) e. CC ) | 
						
							| 51 | 50 | 3adant1 |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( T x. ( C ` j ) ) e. CC ) | 
						
							| 52 | 44 48 51 | subsub4d |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( ( A ` j ) - ( ( 1 - T ) x. ( A ` j ) ) ) - ( T x. ( C ` j ) ) ) = ( ( A ` j ) - ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) ) | 
						
							| 53 | 26 43 52 | 3eqtr2rd |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( A ` j ) - ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) = ( T x. ( ( A ` j ) - ( C ` j ) ) ) ) | 
						
							| 54 | 53 | oveq1d |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( ( A ` j ) - ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) ^ 2 ) = ( ( T x. ( ( A ` j ) - ( C ` j ) ) ) ^ 2 ) ) | 
						
							| 55 |  | simp3 |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> T e. CC ) | 
						
							| 56 |  | subcl |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC ) -> ( ( A ` j ) - ( C ` j ) ) e. CC ) | 
						
							| 57 | 56 | 3adant3 |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( A ` j ) - ( C ` j ) ) e. CC ) | 
						
							| 58 | 55 57 | sqmuld |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( T x. ( ( A ` j ) - ( C ` j ) ) ) ^ 2 ) = ( ( T ^ 2 ) x. ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) ) | 
						
							| 59 | 54 58 | eqtrd |  |-  ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) -> ( ( ( A ` j ) - ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) ^ 2 ) = ( ( T ^ 2 ) x. ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) ) | 
						
							| 60 | 24 59 | sylan9eqr |  |-  ( ( ( ( A ` j ) e. CC /\ ( C ` j ) e. CC /\ T e. CC ) /\ ( B ` j ) = ( ( ( 1 - T ) x. ( A ` j ) ) + ( T x. ( C ` j ) ) ) ) -> ( ( ( A ` j ) - ( B ` j ) ) ^ 2 ) = ( ( T ^ 2 ) x. ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) ) | 
						
							| 61 | 3 6 12 22 60 | syl31anc |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> ( ( ( A ` j ) - ( B ` j ) ) ^ 2 ) = ( ( T ^ 2 ) x. ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) ) | 
						
							| 62 | 61 | sumeq2dv |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) -> sum_ j e. ( 1 ... N ) ( ( ( A ` j ) - ( B ` j ) ) ^ 2 ) = sum_ j e. ( 1 ... N ) ( ( T ^ 2 ) x. ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) ) | 
						
							| 63 |  | fzfid |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) -> ( 1 ... N ) e. Fin ) | 
						
							| 64 | 8 | resqcld |  |-  ( T e. ( 0 [,] 1 ) -> ( T ^ 2 ) e. RR ) | 
						
							| 65 | 64 | recnd |  |-  ( T e. ( 0 [,] 1 ) -> ( T ^ 2 ) e. CC ) | 
						
							| 66 | 65 | adantr |  |-  ( ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) -> ( T ^ 2 ) e. CC ) | 
						
							| 67 | 66 | 3ad2ant3 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) -> ( T ^ 2 ) e. CC ) | 
						
							| 68 | 2 | 3adant1 |  |-  ( ( N e. NN /\ A e. ( EE ` N ) /\ j e. ( 1 ... N ) ) -> ( A ` j ) e. CC ) | 
						
							| 69 | 68 | 3adant2r |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ j e. ( 1 ... N ) ) -> ( A ` j ) e. CC ) | 
						
							| 70 | 5 | 3adant1 |  |-  ( ( N e. NN /\ C e. ( EE ` N ) /\ j e. ( 1 ... N ) ) -> ( C ` j ) e. CC ) | 
						
							| 71 | 70 | 3adant2l |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ j e. ( 1 ... N ) ) -> ( C ` j ) e. CC ) | 
						
							| 72 | 69 71 | subcld |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ j e. ( 1 ... N ) ) -> ( ( A ` j ) - ( C ` j ) ) e. CC ) | 
						
							| 73 | 72 | sqcld |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ j e. ( 1 ... N ) ) -> ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) e. CC ) | 
						
							| 74 | 73 | 3expa |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) ) /\ j e. ( 1 ... N ) ) -> ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) e. CC ) | 
						
							| 75 | 74 | 3adantl3 |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) /\ j e. ( 1 ... N ) ) -> ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) e. CC ) | 
						
							| 76 | 63 67 75 | fsummulc2 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) -> ( ( T ^ 2 ) x. sum_ j e. ( 1 ... N ) ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) = sum_ j e. ( 1 ... N ) ( ( T ^ 2 ) x. ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) ) | 
						
							| 77 | 62 76 | eqtr4d |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( T e. ( 0 [,] 1 ) /\ A. i e. ( 1 ... N ) ( B ` i ) = ( ( ( 1 - T ) x. ( A ` i ) ) + ( T x. ( C ` i ) ) ) ) ) -> sum_ j e. ( 1 ... N ) ( ( ( A ` j ) - ( B ` j ) ) ^ 2 ) = ( ( T ^ 2 ) x. sum_ j e. ( 1 ... N ) ( ( ( A ` j ) - ( C ` j ) ) ^ 2 ) ) ) |