Para hallar los extremos hay que resolver la ecuación
dxdf(x)=0(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
dxdf(x)=primera derivada8log(x)cos(8x)+xsin(8x)=0Resolvermos esta ecuaciónRaíces de esta ecuación
x1=18.2608018697284x2=50.0692126598985x3=74.0238259387079x4=20.2242596466284x5=46.1422304740309x6=52.0327043123183x7=8.05126157419965x8=94.0514666289506x9=42.2152501734583x10=33.9686010425383x11=6.08825647051074x12=75.9873197912678x13=88.160983409589x14=4.12601187626081x15=44.1787400527981x16=28.0781512030948x17=26.1146723269008x18=24.151196695783x19=64.2063583272187x20=55.9596885195547x21=96.0149611276345x22=2.16913055800871x23=11.9778473453662x24=32.0051160175556x25=48.1057213634398x26=77.9508137326498x27=22.1877253166599x28=62.2428652166406x29=70.0968385331794x30=30.0416326076808x31=59.4939751552921x32=84.2339948628895x33=82.2705006820316x34=97.9784556673887x35=79.9143077556694x36=19.0461838505964x37=72.0603321830063x38=92.0879721742245x39=40.2517609256839x40=53.9961962776884x41=10.0145037528058x42=90.1244777666158x43=86.19748910695x44=66.1698515930582x45=60.2793722782135x46=16.2973554021834x47=68.133344999376x48=38.2882724195937Signos de extremos en los puntos:
(18.260801869728397, 2.90474872256889)
(50.06921265989852, -3.91340550510024)
(74.02382593870792, 4.30438668229243)
(20.224259646628404, -3.00687650418207)
(46.142230474030924, -3.83172763538649)
(52.03270431231832, 3.9518717197843)
(8.05126157419965, 2.08577101805123)
(94.0514666289506, -4.54384195539348)
(42.21525017345833, -3.74278036300954)
(33.96860104253829, 3.52543467864806)
(6.0882564705107445, -1.80624507738833)
(75.98731979126781, -4.33056616907704)
(88.16098340958898, 4.47916427576092)
(4.126011876260811, 1.41698761365426)
(44.178740052798084, 3.78824262245249)
(28.078151203094833, -3.33498876526801)
(26.11467232690082, 3.26249380317905)
(24.151196695783007, -3.18432972525899)
(64.2063583272187, -4.16210178983199)
(55.959688519554746, 4.02463096376719)
(96.01496112763455, 4.56450383874468)
(2.1691305580087143, -0.772190944810158)
(11.977847345366225, 2.48303695912207)
(32.00511601755564, -3.465893564999)
(48.10572136343984, 3.87340024572955)
(77.95081373264978, 4.35607773945398)
(22.187725316659915, 3.09953410234481)
(62.24286521664063, 4.13104342563488)
(70.09683853317941, 4.24987731951455)
(30.0416326076808, 3.40258162911481)
(59.493975155292084, -4.08587450932505)
(84.23399486288952, 4.43359833088473)
(82.2705006820316, -4.41001234526697)
(97.97845566738872, -4.58474743686736)
(79.91430775566938, -4.38095462828886)
(19.04618385059643, 2.94685945047606)
(72.06033218300631, -4.27750336339258)
(92.08797217422446, 4.52274413575183)
(40.25176092568393, 3.69515244768311)
(53.996196277688384, -3.98891293302926)
(10.014503752805776, -2.30400060847168)
(90.12447776661581, -4.50119158735671)
(86.19748910695003, -4.45664081262032)
(66.16985159305824, 4.19222451958539)
(60.27937227821351, -4.0989894357339)
(16.297355402183374, -2.79099231053969)
(68.13334499937596, -4.221466342221)
(38.28827241959366, -3.64514218416585)
Intervalos de crecimiento y decrecimiento de la función:Hallemos los intervalos donde la función crece y decrece y también los puntos mínimos y máximos de la función, para lo cual miramos cómo se comporta la función en los extremos con desviación mínima del extremo:
Puntos mínimos de la función:
x1=50.0692126598985x2=20.2242596466284x3=46.1422304740309x4=94.0514666289506x5=42.2152501734583x6=6.08825647051074x7=75.9873197912678x8=28.0781512030948x9=24.151196695783x10=64.2063583272187x11=2.16913055800871x12=32.0051160175556x13=59.4939751552921x14=82.2705006820316x15=97.9784556673887x16=79.9143077556694x17=72.0603321830063x18=53.9961962776884x19=10.0145037528058x20=90.1244777666158x21=86.19748910695x22=60.2793722782135x23=16.2973554021834x24=68.133344999376x25=38.2882724195937Puntos máximos de la función:
x25=18.2608018697284x25=74.0238259387079x25=52.0327043123183x25=8.05126157419965x25=33.9686010425383x25=88.160983409589x25=4.12601187626081x25=44.1787400527981x25=26.1146723269008x25=55.9596885195547x25=96.0149611276345x25=11.9778473453662x25=48.1057213634398x25=77.9508137326498x25=22.1877253166599x25=62.2428652166406x25=70.0968385331794x25=30.0416326076808x25=84.2339948628895x25=19.0461838505964x25=92.0879721742245x25=40.2517609256839x25=66.1698515930582Decrece en los intervalos
[97.9784556673887,∞)Crece en los intervalos
(−∞,2.16913055800871]