Expression 62: StartFraction, 1 Over "n" plus 1 , EndFraction "f" left parenthesis, StartFraction, "k" Over "n" plus 1 , EndFraction , right parenthesis less than or equal to StartFraction, 1 Over "n" , EndFraction "f" left parenthesis, StartFraction, "k" Over "n" , EndFraction , right parenthesis plus StartFraction, "a" "k" plus "b" Over "n" plus 1 , EndFraction "f" left parenthesis, StartFraction, "k" plus 1 Over "n" , EndFraction , right parenthesis minus left parenthesis, StartFraction, "a" "k" plus "b" Over "n" plus 1 , EndFraction plus StartFraction, 1 Over "n" left parenthesis, "n" plus 1 , right parenthesis , EndFraction , right parenthesis "f" left parenthesis, StartFraction, "k" Over "n" , EndFraction , right parenthesis1n+1fkn+1≤1nfkn+ak+bn+1fk+1n−ak+bn+1+1nn+1fkn
add slider:
62
Si on somme sur tous les k
63
Expression 64:
64
Expression 65:
65
Expression 66:
66
Expression 67:
67
Expression 68: StartFraction, 1 Over 1 plus StartNestedFraction, left parenthesis, "N" plus 2 , right parenthesis "x" NestedOver left parenthesis, "N" plus 1 , right parenthesis squared , EndNestedFraction plus StartNestedFraction, left parenthesis, "N" plus 2 , right parenthesis squared "x" squared NestedOver left parenthesis, "N" plus 1 , right parenthesis to the 4th power , EndNestedFraction , EndFraction minus StartFraction, 1 Over 1 plus StartNestedFraction, "x" NestedOver "N" , EndNestedFraction plus StartNestedFraction, "x" squared NestedOver "N" squared , EndNestedFraction , EndFraction11+N+2xN+12+N+22x2N+14−11+xN+x2N2
68
Expression 69: StartFraction, "x" left parenthesis, "N" left parenthesis, "N" plus 1 , right parenthesis squared plus left parenthesis, 2 "N" squared plus 4 "N" plus 1 , right parenthesis "x" , right parenthesis Over left parenthesis, "N" squared plus "N" "x" plus "x" squared , right parenthesis left parenthesis, left parenthesis, "N" plus 1 , right parenthesis to the 4th power plus left parenthesis, "N" plus 2 , right parenthesis left parenthesis, "N" plus 1 , right parenthesis squared "x" plus left parenthesis, "N" plus 2 , right parenthesis squared "x" squared , right parenthesis , EndFractionxNN+12+2N2+4N+1xN2+Nx+x2N+14+N+2N+12x+N+22x2
69
Expression 70: Start sum from "k" equals 1 to 999, end sum, StartFraction, "k" left parenthesis, "n" left parenthesis, "n" plus 1 , right parenthesis squared plus left parenthesis, 2 "n" squared plus 4 "n" plus 1 , right parenthesis "k" , right parenthesis Over left parenthesis, "n" squared plus "n" "k" plus "k" squared , right parenthesis left parenthesis, left parenthesis, "n" plus 1 , right parenthesis to the 4th power plus left parenthesis, "n" plus 2 , right parenthesis left parenthesis, "n" plus 1 , right parenthesis squared "k" plus left parenthesis, "n" plus 2 , right parenthesis squared "k" squared , right parenthesis , EndFraction999∑k=1knn+12+2n2+4n+1kn2+nk+k2n+14+n+2n+12k+n+22k2
70
Expression 71: StartFraction, 1 Over 2 "n" left parenthesis, "n" plus 1 , right parenthesis , EndFraction12nn+1
71
Expression 72: "N" equals 1N=1
11
2020
72
Expression 73:
73
Expression 74: StartFraction, "x" Over 1 plus StartNestedFraction, "x" plus 1 NestedOver "N" plus 1 , EndNestedFraction plus left parenthesis, StartNestedFraction, "x" plus 1 NestedOver "N" plus 1 , EndNestedFraction , right parenthesis squared , EndFractionx1+x+1N+1+x+1N+12
74
Expression 75: 1 plus StartFraction, 1 Over pi "n" , EndFraction co tangent left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis1+1πncotπ2n
75
Expression 76: "g" prime prime left parenthesis, "x" , right parenthesisg′′x
76
Expression 77:
77
Expression 78: StartFraction, 1 Over "n" , EndFraction Start sum from "k" equals 1 to "n" , end sum, "g" left parenthesis, StartFraction, "k" Over "n" , EndFraction , right parenthesis equals alpha StartFraction, 1 Over "n" , EndFraction co tangent left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis plus StartFraction, beta Over 2 , EndFraction plus StartFraction, lambda Over 4 , EndFraction1nn∑k=1gkn=α1ncotπ2n+β2+λ4
78
Expression 79: "h" left parenthesis, "x" , right parenthesis equals "f" left parenthesis, "x" , right parenthesis minus "g" left parenthesis, "x" , right parenthesishx=fx−gx
79
Expression 80: "H" left parenthesis, "x" , right parenthesis equals StartFraction, 1 Over "n" , EndFraction Start sum from "k" equals 1 to "n" , end sum, "h" left parenthesis, StartFraction, "k" Over "n" , EndFraction , right parenthesis minus StartFraction, "h" left parenthesis, 1 half , right parenthesis minus "h" left parenthesis, 0 , right parenthesis Over "n" , EndFractionHx=1nn∑k=1hkn−h12−h0n
80
Expression 81: "R" Subscript, "n" plus 1 , Baseline left parenthesis, "f" , right parenthesis minus "R" Subscript, "n" , Baseline left parenthesis, "f" , right parenthesis equals "R" Subscript, "n" plus 1 , Baseline left parenthesis, "h" , right parenthesis minus "R" Subscript, "n" , Baseline left parenthesis, "h" , right parenthesis plus left parenthesis, StartFraction, cot left parenthesis, StartNestedFraction, pi NestedOver 2 left parenthesis, "n" plus 1 , right parenthesis , EndNestedFraction , right parenthesis Over pi left parenthesis, "n" plus 1 , right parenthesis , EndFraction minus StartFraction, cot left parenthesis, StartNestedFraction, pi NestedOver 2 "n" , EndNestedFraction , right parenthesis Over pi "n" , EndFraction , right parenthesisRn+1f−Rnf=Rn+1h−Rnh+cotπ2n+1πn+1−cotπ2nπn
81
Expression 82: 99 StartFraction, 1 Over "n" , EndFraction Start sum from "k" equals 1 to "n" , end sum, "h" left parenthesis, StartFraction, "k" Over "n" , EndFraction , right parenthesis991nn∑k=1hkn
82
Expression 83: "h" prime left parenthesis, "x" , right parenthesish′x
83
Expression 84: "h" prime prime left parenthesis, "x" , right parenthesish′′x
84
Expression 85: StartFraction, 6 "x" left parenthesis, "x" minus 1 , right parenthesis Over left parenthesis, 1 minus "x" plus "x" squared , right parenthesis cubed , EndFraction plus alpha pi squared sine left parenthesis, pi "x" , right parenthesis minus 2 pi squared left parenthesis, left parenthesis, beta plus lambda , right parenthesis cos left parenthesis, 2 pi "x" , right parenthesis minus lambda cos left parenthesis, 4 pi "x" , right parenthesis , right parenthesis6xx−11−x+x23+απ2sinπx−2π2β+λcos2πx−λcos4πx
85
Expression 86: alpha equals StartFraction, 1 Over pi , EndFractionα=1π
equals=
0.3 1 8 3 0 9 8 8 6 1 8 40.318309886184
86
Expression 87: beta equals 0β=0
00
.1.1
87
Expression 88: lambda equals StartFraction, "f" prime prime prime left parenthesis, 0 , right parenthesis plus pi squared Over 6 pi cubed , EndFractionλ=f′′′0+π26π3
equals=
0.0 8 5 3 0 3 1 8 2 1 3 0 50.0853031821305
88
Expression 89:
89
Expression 90:
90
Expression 91: 1 third minus alpha minus beta13−α−β
equals=
0.0 1 5 0 2 3 4 4 7 1 4 9 50.0150234471495
91
Expression 92:
92
Expression 93: min left parenthesis, 4 left parenthesis, alpha plus beta minus 1 third , right parenthesis , StartFraction, 4 left parenthesis, 3 alpha plus 3 beta minus 1 , right parenthesis plus 2 pi alpha Over 5 , EndFraction , right parenthesismin4α+β−13,43α+3β−1+2πα5
Expression 94: 3 alpha left parenthesis, 2 "n" cot left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis minus pi csc squared left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis , right parenthesis plus 8 left parenthesis, alpha plus beta minus 1 third , right parenthesis3α2ncotπ2n−πcsc2π2n+8α+β−13
94
Expression 95: beta less than or equal to 1 third minus left parenthesis, 1 minus StartFraction, pi Over 4 , EndFraction , right parenthesis alphaβ≤13−1−π4α
95
La fonction
96
Expression 97: "R" Subscript, "n" , Baseline left parenthesis, "h" , right parenthesis minus StartFraction, "h" left parenthesis, 1 half , right parenthesis minus "h" left parenthesis, 0 , right parenthesis Over "n" , EndFractionRnh−h12−h0n
97
est croissante (tant qu'elle est convexe). Elle est aussi égale à (pour n>=2)
98
Expression 99: "R" Subscript, "n" , Baseline left parenthesis, "f" , right parenthesis minus "R" Subscript, "n" , Baseline left parenthesis, "g" , right parenthesis minus StartFraction, "h" left parenthesis, 1 half , right parenthesis minus "h" left parenthesis, 0 , right parenthesis Over "n" , EndFraction equals "R" Subscript, "n" , Baseline left parenthesis, "f" , right parenthesis minus alpha StartFraction, 1 Over "n" , EndFraction co tangent left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis minus StartFraction, beta Over 2 , EndFraction minus StartFraction, lambda Over 12 , EndFraction minus StartFraction, 1 third minus alpha minus beta plus StartNestedFraction, lambda NestedOver 4 , EndNestedFraction Over "n" , EndFraction minus StartFraction, lambda Over 6 , EndFraction StartFraction, 1 Over "n" squared , EndFractionRnf−Rng−h12−h0n=Rnf−α1ncotπ2n−β2−λ12−13−α−β+λ4n−λ61n2
99
Donc (pour n>=2)
100
Expression 101: "R" Subscript, "n" , Baseline left parenthesis, "f" , right parenthesis equals left parenthesis, "R" Subscript, "n" , Baseline left parenthesis, "h" , right parenthesis minus StartFraction, "h" left parenthesis, 1 half , right parenthesis minus "h" left parenthesis, 0 , right parenthesis Over "n" , EndFraction , right parenthesis plus left parenthesis, alpha StartFraction, 1 Over "n" , EndFraction cot left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis plus StartFraction, beta Over 2 , EndFraction plus StartFraction, lambda Over 12 , EndFraction plus StartFraction, 1 third minus alpha minus beta plus StartNestedFraction, lambda NestedOver 4 , EndNestedFraction Over "n" , EndFraction plus StartFraction, lambda Over 6 , EndFraction StartFraction, 1 Over "n" squared , EndFraction , right parenthesisRnf=Rnh−h12−h0n+α1ncotπ2n+β2+λ12+13−α−β+λ4n+λ61n2
101
La seconde partie est égale à (à une constante près)
102
Expression 103: alpha StartFraction, 1 Over "n" , EndFraction co tangent left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis plus StartFraction, 1 third minus alpha minus beta plus StartNestedFraction, lambda NestedOver 4 , EndNestedFraction Over "n" , EndFraction plus StartFraction, lambda Over 6 , EndFraction StartFraction, 1 Over "n" squared , EndFractionα1ncotπ2n+13−α−β+λ4n+λ61n2
103
sa dérivée est égale à
104
Expression 105: StartFraction, 2 "n" left parenthesis, 3 alpha plus 3 beta minus 1 minus StartNestedFraction, 3 lambda NestedOver 4 , EndNestedFraction , right parenthesis minus 6 alpha "n" cot left parenthesis, StartNestedFraction, pi NestedOver 2 "n" , EndNestedFraction , right parenthesis plus 3 pi alpha csc squared left parenthesis, StartNestedFraction, pi NestedOver 2 "n" , EndNestedFraction , right parenthesis minus 2 lambda Over 6 "n" cubed , EndFraction2n3α+3β−1−3λ4−6αncotπ2n+3παcsc2π2n−2λ6n3
105
qui est positive si ça est vrai pour tout n>2
106
Expression 107: 2 "n" left parenthesis, 3 alpha plus 3 beta minus 1 minus StartFraction, 3 lambda Over 4 , EndFraction , right parenthesis greater than or equal to 3 alpha left parenthesis, 2 "n" cot left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis minus pi csc squared left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis , right parenthesis plus 2 lambda2n3α+3β−1−3λ4≥3α2ncotπ2n−πcsc2π2n+2λ
107
Or, la partie de droite est bornée et satisfait
108
Expression 109: 2 lambda minus 3 pi alpha less than or equal to 3 alpha left parenthesis, 2 "n" cot left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis minus pi csc squared left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis , right parenthesis plus 2 lambda less than or equal to 2 lambda minus 2 pi alpha2λ−3πα≤3α2ncotπ2n−πcsc2π2n+2λ≤2λ−2πα
109
Ainsi, il faut absolument avoir 3\alpha+3\beta-1-\frac{3\lambda}{4}>0 sinon éventuellement l'inégalité ne sera pas satisfaite. Inversement, si 3\alpha+3\beta-1-\frac{3\lambda}{4}>0, alors si
110
Expression 111: 4 left parenthesis, 3 alpha plus 3 beta minus 1 minus StartFraction, 3 lambda Over 4 , EndFraction , right parenthesis greater than or equal to 2 lambda minus 2 pi alpha43α+3β−1−3λ4≥2λ−2πα
111
Expression 112: 4 left parenthesis, 3 alpha plus 3 beta minus 1 , right parenthesis greater than or equal to 5 lambda minus 2 pi alpha43α+3β−1≥5λ−2πα
112
est satisfait, on aura
113
Expression 114: 2 "n" left parenthesis, 3 alpha plus 3 beta minus 1 minus StartFraction, 3 lambda Over 4 , EndFraction , right parenthesis greater than or equal to 4 left parenthesis, 3 alpha plus 3 beta minus 1 minus StartFraction, 3 lambda Over 4 , EndFraction , right parenthesis greater than or equal to 2 lambda minus 2 pi alpha greater than or equal to 3 alpha left parenthesis, 2 "n" cot left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis minus pi csc squared left parenthesis, StartFraction, pi Over 2 "n" , EndFraction , right parenthesis , right parenthesis2n3α+3β−1−3λ4≥43α+3β−1−3λ4≥2λ−2πα≥3α2ncotπ2n−πcsc2π2n
114
et l'inégalité est satisfaite. Ainsi, la seconde fonction est croissante "SI ET SEULEMENT SI" 3\alpha+3\beta-1-\frac{3\lambda}{4}>0.
115
Expression 116: StartFraction, 4 left parenthesis, 3 alpha plus 3 beta minus 1 , right parenthesis plus 2 pi alpha Over 5 , EndFraction greater than or equal to lambda43α+3β−1+2πα5≥λ
116
Expression 117: 4 left parenthesis, alpha plus beta minus 1 third , right parenthesis greater than lambda4α+β−13>λ