Metamath Proof Explorer


Theorem cmvth

Description: Cauchy's Mean Value Theorem. If F , G are real continuous functions on [ A , B ] differentiable on ( A , B ) , then there is some x e. ( A , B ) such that F ' ( x ) / G ' ( x ) = ( F ( A ) - F ( B ) ) / ( G ( A ) - G ( B ) ) . (We express the condition without division, so that we need no nonzero constraints.) (Contributed by Mario Carneiro, 29-Dec-2016) Avoid ax-mulf . (Revised by GG, 16-Mar-2025)

Ref Expression
Hypotheses cmvth.a φ A
cmvth.b φ B
cmvth.lt φ A < B
cmvth.f φ F : A B cn
cmvth.g φ G : A B cn
cmvth.df φ dom F = A B
cmvth.dg φ dom G = A B
Assertion cmvth φ x A B F B F A G x = G B G A F x

Proof

Step Hyp Ref Expression
1 cmvth.a φ A
2 cmvth.b φ B
3 cmvth.lt φ A < B
4 cmvth.f φ F : A B cn
5 cmvth.g φ G : A B cn
6 cmvth.df φ dom F = A B
7 cmvth.dg φ dom G = A B
8 eqid TopOpen fld = TopOpen fld
9 8 subcn TopOpen fld × t TopOpen fld Cn TopOpen fld
10 cncff F : A B cn F : A B
11 4 10 syl φ F : A B
12 1 rexrd φ A *
13 2 rexrd φ B *
14 1 2 3 ltled φ A B
15 ubicc2 A * B * A B B A B
16 12 13 14 15 syl3anc φ B A B
17 11 16 ffvelcdmd φ F B
18 lbicc2 A * B * A B A A B
19 12 13 14 18 syl3anc φ A A B
20 11 19 ffvelcdmd φ F A
21 17 20 resubcld φ F B F A
22 21 recnd φ F B F A
23 22 adantr φ z A B F B F A
24 cncff G : A B cn G : A B
25 5 24 syl φ G : A B
26 25 ffvelcdmda φ z A B G z
27 26 recnd φ z A B G z
28 ovmpot F B F A G z F B F A u , v u v G z = F B F A G z
29 23 27 28 syl2anc φ z A B F B F A u , v u v G z = F B F A G z
30 29 eqeq2d φ z A B w = F B F A u , v u v G z w = F B F A G z
31 30 pm5.32da φ z A B w = F B F A u , v u v G z z A B w = F B F A G z
32 31 opabbidv φ z w | z A B w = F B F A u , v u v G z = z w | z A B w = F B F A G z
33 df-mpt z A B F B F A G z = z w | z A B w = F B F A G z
34 32 33 eqtr4di φ z w | z A B w = F B F A u , v u v G z = z A B F B F A G z
35 df-mpt z A B F B F A u , v u v G z = z w | z A B w = F B F A u , v u v G z
36 8 mpomulcn u , v u v TopOpen fld × t TopOpen fld Cn TopOpen fld
37 1 2 iccssred φ A B
38 ax-resscn
39 37 38 sstrdi φ A B
40 38 a1i φ
41 cncfmptc F B F A A B z A B F B F A : A B cn
42 21 39 40 41 syl3anc φ z A B F B F A : A B cn
43 25 feqmptd φ G = z A B G z
44 43 5 eqeltrrd φ z A B G z : A B cn
45 simpl F B F A G z F B F A
46 45 recnd F B F A G z F B F A
47 simpr F B F A G z G z
48 47 recnd F B F A G z G z
49 28 eqcomd F B F A G z F B F A G z = F B F A u , v u v G z
50 46 48 49 syl2anc F B F A G z F B F A G z = F B F A u , v u v G z
51 remulcl F B F A G z F B F A G z
52 50 51 eqeltrrd F B F A G z F B F A u , v u v G z
53 8 36 42 44 38 52 cncfmpt2ss φ z A B F B F A u , v u v G z : A B cn
54 35 53 eqeltrrid φ z w | z A B w = F B F A u , v u v G z : A B cn
55 34 54 eqeltrrd φ z A B F B F A G z : A B cn
56 25 16 ffvelcdmd φ G B
57 25 19 ffvelcdmd φ G A
58 56 57 resubcld φ G B G A
59 58 adantr φ z A B G B G A
60 59 recnd φ z A B G B G A
61 11 ffvelcdmda φ z A B F z
62 61 recnd φ z A B F z
63 ovmpot G B G A F z G B G A u , v u v F z = G B G A F z
64 60 62 63 syl2anc φ z A B G B G A u , v u v F z = G B G A F z
65 64 eqeq2d φ z A B w = G B G A u , v u v F z w = G B G A F z
66 65 pm5.32da φ z A B w = G B G A u , v u v F z z A B w = G B G A F z
67 66 opabbidv φ z w | z A B w = G B G A u , v u v F z = z w | z A B w = G B G A F z
68 df-mpt z A B G B G A F z = z w | z A B w = G B G A F z
69 67 68 eqtr4di φ z w | z A B w = G B G A u , v u v F z = z A B G B G A F z
70 df-mpt z A B G B G A u , v u v F z = z w | z A B w = G B G A u , v u v F z
71 cncfmptc G B G A A B z A B G B G A : A B cn
72 58 39 40 71 syl3anc φ z A B G B G A : A B cn
73 11 feqmptd φ F = z A B F z
74 73 4 eqeltrrd φ z A B F z : A B cn
75 simpl G B G A F z G B G A
76 75 recnd G B G A F z G B G A
77 simpr G B G A F z F z
78 77 recnd G B G A F z F z
79 63 eqcomd G B G A F z G B G A F z = G B G A u , v u v F z
80 76 78 79 syl2anc G B G A F z G B G A F z = G B G A u , v u v F z
81 remulcl G B G A F z G B G A F z
82 80 81 eqeltrrd G B G A F z G B G A u , v u v F z
83 8 36 72 74 38 82 cncfmpt2ss φ z A B G B G A u , v u v F z : A B cn
84 70 83 eqeltrrid φ z w | z A B w = G B G A u , v u v F z : A B cn
85 69 84 eqeltrrd φ z A B G B G A F z : A B cn
86 resubcl F B F A G z G B G A F z F B F A G z G B G A F z
87 8 9 55 85 38 86 cncfmpt2ss φ z A B F B F A G z G B G A F z : A B cn
88 23 27 mulcld φ z A B F B F A G z
89 59 61 remulcld φ z A B G B G A F z
90 89 recnd φ z A B G B G A F z
91 88 90 subcld φ z A B F B F A G z G B G A F z
92 8 tgioo2 topGen ran . = TopOpen fld 𝑡
93 iccntr A B int topGen ran . A B = A B
94 1 2 93 syl2anc φ int topGen ran . A B = A B
95 40 37 91 92 8 94 dvmptntr φ dz A B F B F A G z G B G A F z d z = dz A B F B F A G z G B G A F z d z
96 reelprrecn
97 96 a1i φ
98 ioossicc A B A B
99 98 sseli z A B z A B
100 99 88 sylan2 φ z A B F B F A G z
101 ovexd φ z A B F B F A G z V
102 99 27 sylan2 φ z A B G z
103 fvexd φ z A B G z V
104 43 oveq2d φ D G = dz A B G z d z
105 dvf G : dom G
106 7 feq2d φ G : dom G G : A B
107 105 106 mpbii φ G : A B
108 107 feqmptd φ D G = z A B G z
109 40 37 27 92 8 94 dvmptntr φ dz A B G z d z = dz A B G z d z
110 104 108 109 3eqtr3rd φ dz A B G z d z = z A B G z
111 97 102 103 110 22 dvmptcmul φ dz A B F B F A G z d z = z A B F B F A G z
112 99 90 sylan2 φ z A B G B G A F z
113 ovexd φ z A B G B G A F z V
114 99 62 sylan2 φ z A B F z
115 fvexd φ z A B F z V
116 73 oveq2d φ D F = dz A B F z d z
117 dvf F : dom F
118 6 feq2d φ F : dom F F : A B
119 117 118 mpbii φ F : A B
120 119 feqmptd φ D F = z A B F z
121 40 37 62 92 8 94 dvmptntr φ dz A B F z d z = dz A B F z d z
122 116 120 121 3eqtr3rd φ dz A B F z d z = z A B F z
123 58 recnd φ G B G A
124 97 114 115 122 123 dvmptcmul φ dz A B G B G A F z d z = z A B G B G A F z
125 97 100 101 111 112 113 124 dvmptsub φ dz A B F B F A G z G B G A F z d z = z A B F B F A G z G B G A F z
126 95 125 eqtrd φ dz A B F B F A G z G B G A F z d z = z A B F B F A G z G B G A F z
127 126 dmeqd φ dom dz A B F B F A G z G B G A F z d z = dom z A B F B F A G z G B G A F z
128 ovex F B F A G z G B G A F z V
129 eqid z A B F B F A G z G B G A F z = z A B F B F A G z G B G A F z
130 128 129 dmmpti dom z A B F B F A G z G B G A F z = A B
131 127 130 eqtrdi φ dom dz A B F B F A G z G B G A F z d z = A B
132 17 recnd φ F B
133 57 recnd φ G A
134 132 133 mulcld φ F B G A
135 20 recnd φ F A
136 56 recnd φ G B
137 135 136 mulcld φ F A G B
138 135 133 mulcld φ F A G A
139 134 137 138 nnncan2d φ F B G A - F A G A - F A G B F A G A = F B G A F A G B
140 132 136 mulcld φ F B G B
141 140 137 134 nnncan1d φ F B G B - F A G B - F B G B F B G A = F B G A F A G B
142 139 141 eqtr4d φ F B G A - F A G A - F A G B F A G A = F B G B - F A G B - F B G B F B G A
143 132 135 133 subdird φ F B F A G A = F B G A F A G A
144 123 135 mulcomd φ G B G A F A = F A G B G A
145 135 136 133 subdid φ F A G B G A = F A G B F A G A
146 144 145 eqtrd φ G B G A F A = F A G B F A G A
147 143 146 oveq12d φ F B F A G A G B G A F A = F B G A - F A G A - F A G B F A G A
148 132 135 136 subdird φ F B F A G B = F B G B F A G B
149 123 132 mulcomd φ G B G A F B = F B G B G A
150 132 136 133 subdid φ F B G B G A = F B G B F B G A
151 149 150 eqtrd φ G B G A F B = F B G B F B G A
152 148 151 oveq12d φ F B F A G B G B G A F B = F B G B - F A G B - F B G B F B G A
153 142 147 152 3eqtr4d φ F B F A G A G B G A F A = F B F A G B G B G A F B
154 fveq2 z = A G z = G A
155 154 oveq2d z = A F B F A G z = F B F A G A
156 fveq2 z = A F z = F A
157 156 oveq2d z = A G B G A F z = G B G A F A
158 155 157 oveq12d z = A F B F A G z G B G A F z = F B F A G A G B G A F A
159 eqid z A B F B F A G z G B G A F z = z A B F B F A G z G B G A F z
160 ovex F B F A G z G B G A F z V
161 158 159 160 fvmpt3i A A B z A B F B F A G z G B G A F z A = F B F A G A G B G A F A
162 19 161 syl φ z A B F B F A G z G B G A F z A = F B F A G A G B G A F A
163 fveq2 z = B G z = G B
164 163 oveq2d z = B F B F A G z = F B F A G B
165 fveq2 z = B F z = F B
166 165 oveq2d z = B G B G A F z = G B G A F B
167 164 166 oveq12d z = B F B F A G z G B G A F z = F B F A G B G B G A F B
168 167 159 160 fvmpt3i B A B z A B F B F A G z G B G A F z B = F B F A G B G B G A F B
169 16 168 syl φ z A B F B F A G z G B G A F z B = F B F A G B G B G A F B
170 153 162 169 3eqtr4d φ z A B F B F A G z G B G A F z A = z A B F B F A G z G B G A F z B
171 1 2 3 87 131 170 rolle φ x A B dz A B F B F A G z G B G A F z d z x = 0
172 126 fveq1d φ dz A B F B F A G z G B G A F z d z x = z A B F B F A G z G B G A F z x
173 fveq2 z = x G z = G x
174 173 oveq2d z = x F B F A G z = F B F A G x
175 fveq2 z = x F z = F x
176 175 oveq2d z = x G B G A F z = G B G A F x
177 174 176 oveq12d z = x F B F A G z G B G A F z = F B F A G x G B G A F x
178 177 129 128 fvmpt3i x A B z A B F B F A G z G B G A F z x = F B F A G x G B G A F x
179 172 178 sylan9eq φ x A B dz A B F B F A G z G B G A F z d z x = F B F A G x G B G A F x
180 179 eqeq1d φ x A B dz A B F B F A G z G B G A F z d z x = 0 F B F A G x G B G A F x = 0
181 22 adantr φ x A B F B F A
182 107 ffvelcdmda φ x A B G x
183 181 182 mulcld φ x A B F B F A G x
184 123 adantr φ x A B G B G A
185 119 ffvelcdmda φ x A B F x
186 184 185 mulcld φ x A B G B G A F x
187 183 186 subeq0ad φ x A B F B F A G x G B G A F x = 0 F B F A G x = G B G A F x
188 180 187 bitrd φ x A B dz A B F B F A G z G B G A F z d z x = 0 F B F A G x = G B G A F x
189 188 rexbidva φ x A B dz A B F B F A G z G B G A F z d z x = 0 x A B F B F A G x = G B G A F x
190 171 189 mpbid φ x A B F B F A G x = G B G A F x