Sr Examen

Gráfico de la función y = (5x-6)cosx-5sinx-8

v

Gráfico:

interior superior

Puntos de intersección:

mostrar?

Definida a trozos:

Solución

Ha introducido [src]
f(x) = (5*x - 6)*cos(x) - 5*sin(x) - 8
f(x)=((5x6)cos(x)5sin(x))8f{\left(x \right)} = \left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8
f = (5*x - 6)*cos(x) - 5*sin(x) - 8
Gráfico de la función
02468-8-6-4-2-1010-100100
Puntos de cruce con el eje de coordenadas X
El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
((5x6)cos(x)5sin(x))8=0\left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8 = 0
Resolvermos esta ecuación
Puntos de cruce con el eje X:

Solución numérica
x1=20.2841783563549x_{1} = 20.2841783563549
x2=10.7787837858107x_{2} = -10.7787837858107
x3=80.1182159135069x_{3} = 80.1182159135069
x4=1.78099958956035x_{4} = -1.78099958956035
x5=54.9890275174791x_{5} = 54.9890275174791
x6=86.4008405070432x_{6} = 86.4008405070432
x7=89.5059481914431x_{7} = 89.5059481914431
x8=64.4117948607037x_{8} = -64.4117948607037
x9=76.9346906795607x_{9} = 76.9346906795607
x10=98.9663059029183x_{10} = 98.9663059029183
x11=61.2710459146833x_{11} = 61.2710459146833
x12=58.1295781255191x_{12} = -58.1295781255191
x13=54.9315542271583x_{13} = -54.9315542271583
x14=67.5532852979797x_{14} = 67.5532852979797
x15=48.7073177790812x_{15} = 48.7073177790812
x16=17.3160413345614x_{16} = 17.3160413345614
x17=76.9766953865895x_{17} = -76.9766953865895
x18=83.2593096912827x_{18} = -83.2593096912827
x19=39.2014980193858x_{19} = 39.2014980193858
x20=92.6492798308084x_{20} = -92.6492798308084
x21=17.1370429233044x_{21} = -17.1370429233044
x22=11.0566740712597x_{22} = 11.0566740712597
x23=32.9047302958918x_{23} = 32.9047302958918
x24=48.6425254774914x_{24} = -48.6425254774914
x25=45.5659254437323x_{25} = -45.5659254437323
x26=51.784883509925x_{26} = 51.784883509925
x27=23.4565261495249x_{27} = -23.4565261495249
x28=58.0737512507645x_{28} = 58.0737512507645
x29=7.43904788315296x_{29} = 7.43904788315296
x30=70.6483981823569x_{30} = 70.6483981823569
x31=7.92005804153317x_{31} = -7.92005804153317
x32=4.88002461489479x_{32} = 4.88002461489479
x33=14.1762477702438x_{33} = -14.1762477702438
x34=42.4260578094509x_{34} = 42.4260578094509
x35=45.4944004951236x_{35} = 45.4944004951236
x36=61.219404884124x_{36} = -61.219404884124
x37=42.3518072602855x_{37} = -42.3518072602855
x38=36.1454901783917x_{38} = 36.1454901783917
x39=95.7910897341891x_{39} = 95.7910897341891
x40=80.0786247754862x_{40} = -80.0786247754862
x41=26.7250335819054x_{41} = -26.7250335819054
x42=29.7611692171685x_{42} = -29.7611692171685
x43=89.5420030693364x_{43} = -89.5420030693364
x44=64.361486861137x_{44} = 64.361486861137
x45=73.8356883252877x_{45} = 73.8356883252877
x46=4.23685828013603x_{46} = -4.23685828013603
x47=20.4480896449965x_{47} = -20.4480896449965
x48=13.9331928231935x_{48} = 13.9331928231935
x49=23.5887633356003x_{49} = 23.5887633356003
x50=92.6835421197591x_{50} = 92.6835421197591
x51=51.8475908300552x_{51} = -51.8475908300552
x52=83.2205067471085x_{52} = 83.2205067471085
x53=36.0585415653627x_{53} = -36.0585415653627
x54=70.6941808860606x_{54} = -70.6941808860606
x55=86.3641061131095x_{55} = -86.3641061131095
x56=73.7927584134673x_{56} = -73.7927584134673
x57=33.0042699334544x_{57} = -33.0042699334544
x58=95.8247601594832x_{58} = -95.8247601594832
x59=98.9342038831243x_{59} = -98.9342038831243
x60=39.28473182857x_{60} = -39.28473182857
x61=67.5064012613838x_{61} = -67.5064012613838
x62=29.8660700552484x_{62} = 29.8660700552484
x63=26.6012076617219x_{63} = 26.6012076617219
Puntos de cruce con el eje de coordenadas Y
El gráfico cruce el eje Y cuando x es igual a 0:
sustituimos x = 0 en (5*x - 6)*cos(x) - 5*sin(x) - 8.
8+((6+05)cos(0)5sin(0))-8 + \left(\left(-6 + 0 \cdot 5\right) \cos{\left(0 \right)} - 5 \sin{\left(0 \right)}\right)
Resultado:
f(0)=14f{\left(0 \right)} = -14
Punto:
(0, -14)
Extremos de la función
Para hallar los extremos hay que resolver la ecuación
ddxf(x)=0\frac{d}{d x} f{\left(x \right)} = 0
(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
ddxf(x)=\frac{d}{d x} f{\left(x \right)} =
primera derivada
(5x6)sin(x)=0- \left(5 x - 6\right) \sin{\left(x \right)} = 0
Resolvermos esta ecuación
Raíces de esta ecuación
x1=0x_{1} = 0
x2=65x_{2} = \frac{6}{5}
x3=πx_{3} = \pi
Signos de extremos en los puntos:
(0, -14)

(6/5, -8 - 5*sin(6/5))

(pi, -2 - 5*pi)


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=0x_{1} = 0
x2=πx_{2} = \pi
Puntos máximos de la función:
x2=65x_{2} = \frac{6}{5}
Decrece en los intervalos
[0,65][π,)\left[0, \frac{6}{5}\right] \cup \left[\pi, \infty\right)
Crece en los intervalos
(,0][65,π]\left(-\infty, 0\right] \cup \left[\frac{6}{5}, \pi\right]
Puntos de flexiones
Hallemos los puntos de flexiones, para eso hay que resolver la ecuación
d2dx2f(x)=0\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0
(la segunda derivada es igual a cero),
las raíces de la ecuación obtenida serán los puntos de flexión para el gráfico de la función indicado:
d2dx2f(x)=\frac{d^{2}}{d x^{2}} f{\left(x \right)} =
segunda derivada
((5x6)cos(x)+5sin(x))=0- (\left(5 x - 6\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}) = 0
Resolvermos esta ecuación
Raíces de esta ecuación
x1=36.1550792454209x_{1} = -36.1550792454209
x2=48.7157286870095x_{2} = 48.7157286870095
x3=4.97156717459977x_{3} = 4.97156717459977
x4=0.565442570980802x_{4} = 0.565442570980802
x5=36.1569143606634x_{5} = 36.1569143606634
x6=67.5587846231267x_{6} = -67.5587846231267
x7=73.841192783613x_{7} = 73.841192783613
x8=61.2770612528486x_{8} = -61.2770612528486
x9=33.0181411324871x_{9} = 33.0181411324871
x10=45.5756245577456x_{10} = 45.5756245577456
x11=17.340635932901x_{11} = 17.340635932901
x12=95.8291431101507x_{12} = 95.8291431101507
x13=95.8288817792839x_{13} = -95.8288817792839
x14=42.4344145027915x_{14} = -42.4344145027915
x15=54.9964578817018x_{15} = 54.9964578817018
x16=26.7426677500163x_{16} = 26.7426677500163
x17=86.405533761829x_{17} = 86.405533761829
x18=26.7393141427176x_{18} = -26.7393141427176
x19=58.1370255496473x_{19} = 58.1370255496473
x20=20.4664737743732x_{20} = -20.4664737743732
x21=80.1229087048627x_{21} = -80.1229087048627
x22=83.2643902703279x_{22} = 83.2643902703279
x23=29.8799836128142x_{23} = 29.8799836128142
x24=98.970151270236x_{24} = -98.970151270236
x25=89.5464099009748x_{25} = -89.5464099009748
x26=14.2020025613255x_{26} = -14.2020025613255
x27=4.8755212403945x_{27} = -4.8755212403945
x28=1.88432283078319x_{28} = -1.88432283078319
x29=39.2961515141128x_{29} = 39.2961515141128
x30=92.6879132512385x_{30} = 92.6879132512385
x31=67.5593103871002x_{31} = 67.5593103871002
x32=86.4052123238929x_{32} = -86.4052123238929
x33=11.0962805204051x_{33} = 11.0962805204051
x34=29.8772969409318x_{34} = -29.8772969409318
x35=7.962689643105x_{35} = -7.962689643105
x36=39.2945978038801x_{36} = -39.2945978038801
x37=98.9703962763083x_{37} = 98.9703962763083
x38=51.8551248732361x_{38} = -51.8551248732361
x39=7.99999401830929x_{39} = 7.99999401830929
x40=64.4184662424212x_{40} = 64.4184662424212
x41=14.2138574045673x_{41} = 14.2138574045673
x42=89.5467091846795x_{42} = 89.5467091846795
x43=11.0768489837286x_{43} = -11.0768489837286
x44=33.0159406893315x_{44} = -33.0159406893315
x45=23.6065451223817x_{45} = 23.6065451223817
x46=76.9818100145011x_{46} = -76.9818100145011
x47=80.1232825208474x_{47} = 80.1232825208474
x48=83.2640441243312x_{48} = -83.2640441243312
x49=64.4178879657735x_{49} = -64.4178879657735
x50=70.7002221561763x_{50} = 70.7002221561763
x51=20.4721939838984x_{51} = 20.4721939838984
x52=61.2777003191857x_{52} = 61.2777003191857
x53=54.9956645269298x_{53} = -54.9956645269298
x54=92.6876339081023x_{54} = -92.6876339081023
x55=73.8407526629573x_{55} = -73.8407526629573
x56=70.6997420648082x_{56} = -70.6997420648082
x57=58.136315581613x_{57} = -58.136315581613
x58=45.5744694049456x_{58} = -45.5744694049456
x59=51.8560172118292x_{59} = 51.8560172118292
x60=17.3326660953102x_{60} = -17.3326660953102
x61=42.4357468747913x_{61} = 42.4357468747913
x62=48.7147176221638x_{62} = -48.7147176221638
x63=23.6022420111635x_{63} = -23.6022420111635
x64=76.9822149553835x_{64} = 76.9822149553835
x65=2.30593416045522x_{65} = 2.30593416045522

Intervalos de convexidad y concavidad:
Hallemos los intervales donde la función es convexa o cóncava, para eso veamos cómo se comporta la función en los puntos de flexiones:
Cóncava en los intervalos
[95.8291431101507,)\left[95.8291431101507, \infty\right)
Convexa en los intervalos
(,95.8288817792839]\left(-\infty, -95.8288817792839\right]
Asíntotas horizontales
Hallemos las asíntotas horizontales mediante los límites de esta función con x->+oo y x->-oo
limx(((5x6)cos(x)5sin(x))8)=,\lim_{x \to -\infty}\left(\left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8\right) = \left\langle -\infty, \infty\right\rangle
Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la izquierda:
y=,y = \left\langle -\infty, \infty\right\rangle
limx(((5x6)cos(x)5sin(x))8)=,\lim_{x \to \infty}\left(\left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8\right) = \left\langle -\infty, \infty\right\rangle
Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la derecha:
y=,y = \left\langle -\infty, \infty\right\rangle
Asíntotas inclinadas
Se puede hallar la asíntota inclinada calculando el límite de la función (5*x - 6)*cos(x) - 5*sin(x) - 8, dividida por x con x->+oo y x ->-oo
True

Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la izquierda:
y=xlimx(((5x6)cos(x)5sin(x))8x)y = x \lim_{x \to -\infty}\left(\frac{\left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8}{x}\right)
True

Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la derecha:
y=xlimx(((5x6)cos(x)5sin(x))8x)y = x \lim_{x \to \infty}\left(\frac{\left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8}{x}\right)
Paridad e imparidad de la función
Comprobemos si la función es par o impar mediante las relaciones f = f(-x) и f = -f(-x).
Pues, comprobamos:
((5x6)cos(x)5sin(x))8=(5x6)cos(x)+5sin(x)8\left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8 = \left(- 5 x - 6\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)} - 8
- No
((5x6)cos(x)5sin(x))8=(5x6)cos(x)5sin(x)+8\left(\left(5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)}\right) - 8 = - \left(- 5 x - 6\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)} + 8
- No
es decir, función
no es
par ni impar