Sr Examen

Gráfico de la función y = (1−5x)cosx+5sinx+5

v

Gráfico:

interior superior

Puntos de intersección:

mostrar?

Definida a trozos:

Solución

Ha introducido [src]
f(x) = (1 - 5*x)*cos(x) + 5*sin(x) + 5
f(x)=((15x)cos(x)+5sin(x))+5f{\left(x \right)} = \left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5
f = (1 - 5*x)*cos(x) + 5*sin(x) + 5
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:
((15x)cos(x)+5sin(x))+5=0\left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5 = 0
Resolvermos esta ecuación
Puntos de cruce con el eje X:

Solución numérica
x1=48.6537533341471x_{1} = -48.6537533341471
x2=1.5707963267949x_{2} = -1.5707963267949
x3=29.7784403257546x_{3} = -29.7784403257546
x4=67.5147085184766x_{4} = -67.5147085184766
x5=64.4026493985908x_{5} = -64.4026493985908
x6=80.1106126665397x_{6} = 80.1106126665397
x7=73.8004021241737x_{7} = -73.8004021241737
x8=58.1194640914112x_{8} = -58.1194640914112
x9=61.261056745001x_{9} = 61.261056745001
x10=61.2285014439827x_{10} = -61.2285014439827
x11=7.58479217250512x_{11} = 7.58479217250512
x12=4.27244218881739x_{12} = -4.27244218881739
x13=98.9399957793133x_{13} = -98.9399957793133
x14=42.3645219768016x_{14} = -42.3645219768016
x15=80.0857029190966x_{15} = -80.0857029190966
x16=39.2699081698724x_{16} = -39.2699081698724
x17=23.4775267893224x_{17} = -23.4775267893224
x18=73.8274273593601x_{18} = 73.8274273593601
x19=42.4115008234622x_{19} = 42.4115008234622
x20=67.5442420521806x_{20} = 67.5442420521806
x21=13.9924129739997x_{21} = 13.9924129739997
x22=20.3210355029275x_{22} = 20.3210355029275
x23=32.9867228626928x_{23} = -32.9867228626928
x24=51.7975220849567x_{24} = 51.7975220849567
x25=89.5129984059483x_{25} = 89.5129984059483
x26=4.71238898038469x_{26} = 4.71238898038469
x27=45.5089592620121x_{27} = 45.5089592620121
x28=36.1283155162826x_{28} = 36.1283155162826
x29=70.6858347057703x_{29} = -70.6858347057703
x30=26.7035375555132x_{30} = -26.7035375555132
x31=10.9955742875643x_{31} = 10.9955742875643
x32=86.3706964955773x_{32} = -86.3706964955773
x33=54.9416051597134x_{33} = -54.9416051597134
x34=23.5619449019235x_{34} = 23.5619449019235
x35=95.7976556823929x_{35} = 95.7976556823929
x36=89.5353906273091x_{36} = -89.5353906273091
x37=58.0849162126044x_{37} = 58.0849162126044
x38=70.6574506852969x_{38} = 70.6574506852969
x39=76.9429604655563x_{39} = 76.9429604655563
x40=17.2787595947439x_{40} = 17.2787595947439
x41=26.6278960326346x_{41} = 26.6278960326346
x42=29.845130209103x_{42} = 29.845130209103
x43=54.9778714378214x_{43} = 54.9778714378214
x44=7.85398163397448x_{44} = -7.85398163397448
x45=48.6946861306418x_{45} = 48.6946861306418
x46=83.2281182597067x_{46} = 83.2281182597067
x47=51.8362787842316x_{47} = -51.8362787842316
x48=92.6769832808989x_{48} = 92.6769832808989
x49=86.3937979737193x_{49} = 86.3937979737193
x50=32.9256276905281x_{50} = 32.9256276905281
x51=76.9690200129499x_{51} = -76.9690200129499
x52=64.3714854303815x_{52} = 64.3714854303815
x53=20.4203522483337x_{53} = -20.4203522483337
x54=92.655445258229x_{54} = -92.655445258229
x55=83.2522053201295x_{55} = -83.2522053201295
x56=98.9601685880785x_{56} = 98.9601685880785
x57=95.8185759344887x_{57} = -95.8185759344887
x58=14.1371669411541x_{58} = -14.1371669411541
x59=39.2186618639252x_{59} = 39.2186618639252
x60=17.1637038886979x_{60} = -17.1637038886979
x61=45.553093477052x_{61} = -45.553093477052
x62=36.0731923407939x_{62} = -36.0731923407939
x63=10.8144917732018x_{63} = -10.8144917732018
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 (1 - 5*x)*cos(x) + 5*sin(x) + 5.
(5sin(0)+(10)cos(0))+5\left(5 \sin{\left(0 \right)} + \left(1 - 0\right) \cos{\left(0 \right)}\right) + 5
Resultado:
f(0)=6f{\left(0 \right)} = 6
Punto:
(0, 6)
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
(15x)sin(x)=0- \left(1 - 5 x\right) \sin{\left(x \right)} = 0
Resolvermos esta ecuación
Raíces de esta ecuación
x1=0x_{1} = 0
x2=15x_{2} = \frac{1}{5}
x3=πx_{3} = \pi
Signos de extremos en los puntos:
(0, 6)

(1/5, 5 + 5*sin(1/5))

(pi, 4 + 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=15x_{1} = \frac{1}{5}
Puntos máximos de la función:
x1=0x_{1} = 0
x1=πx_{1} = \pi
Decrece en los intervalos
(,0][15,)\left(-\infty, 0\right] \cup \left[\frac{1}{5}, \infty\right)
Crece en los intervalos
(,15][π,)\left(-\infty, \frac{1}{5}\right] \cup \left[\pi, \infty\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
(5x1)cos(x)+5sin(x)=0\left(5 x - 1\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)} = 0
Resolvermos esta ecuación
Raíces de esta ecuación
x1=80.123124037102x_{1} = 80.123124037102
x2=73.8410059155972x_{2} = 73.8410059155972
x3=26.7411970178799x_{3} = 26.7411970178799
x4=70.6999381552614x_{4} = -70.6999381552614
x5=11.0839647052878x_{5} = -11.0839647052878
x6=95.8290326287034x_{6} = 95.8290326287034
x7=89.5465825298805x_{7} = 89.5465825298805
x8=14.2084316314105x_{8} = 14.2084316314105
x9=39.2954809976045x_{9} = 39.2954809976045
x10=45.574936019056x_{10} = -45.574936019056
x11=4.90579659852922x_{11} = -4.90579659852922
x12=61.2774279428948x_{12} = 61.2774279428948
x13=1.99780072102961x_{13} = -1.99780072102961
x14=92.687748547417x_{14} = -92.687748547417
x15=70.700018148111x_{15} = 70.700018148111
x16=7.97569090752723x_{16} = -7.97569090752723
x17=54.9959867152057x_{17} = -54.9959867152057
x18=80.1230617480093x_{18} = -80.1230617480093
x19=89.546532657964x_{19} = -89.546532657964
x20=11.0871685281105x_{20} = 11.0871685281105
x21=48.7151268569761x_{21} = -48.7151268569761
x22=51.8554866925474x_{22} = -51.8554866925474
x23=0.0998335006317683x_{23} = 0.0998335006317683
x24=45.5751284152112x_{24} = 45.5751284152112
x25=4.92111814008087x_{25} = 4.92111814008087
x26=39.2952222795744x_{26} = -39.2952222795744
x27=26.7406391665229x_{27} = -26.7406391665229
x28=17.3357243420014x_{28} = -17.3357243420014
x29=36.1561200260315x_{29} = 36.1561200260315
x30=64.4182200447873x_{30} = 64.4182200447873
x31=23.6039300842954x_{31} = -23.6039300842954
x32=73.8409325809639x_{32} = -73.8409325809639
x33=102.111573354997x_{33} = 102.111573354997
x34=33.0171852759959x_{34} = 33.0171852759959
x35=33.0168190033189x_{35} = -33.0168190033189
x36=36.1558144992204x_{36} = -36.1558144992204
x37=64.4181236978048x_{37} = -64.4181236978048
x38=83.2641859336504x_{38} = -83.2641859336504
x39=61.2773214714736x_{39} = -61.2773214714736
x40=29.8788115384958x_{40} = 29.8788115384958
x41=86.4053440921774x_{41} = -86.4053440921774
x42=58.1366043086199x_{42} = -58.1366043086199
x43=95.8289890801938x_{43} = -95.8289890801938
x44=58.1367225877178x_{44} = 58.1367225877178
x45=76.9819756809122x_{45} = -76.9819756809122
x46=98.9702927438931x_{46} = 98.9702927438931
x47=48.7152952686795x_{47} = 48.7152952686795
x48=164.939669719649x_{48} = -164.939669719649
x49=86.4053976551305x_{49} = 86.4053976551305
x50=14.2064690412927x_{50} = -14.2064690412927
x51=42.4349514584065x_{51} = -42.4349514584065
x52=76.9820431551352x_{52} = 76.9820431551352
x53=17.3370466092751x_{53} = 17.3370466092751
x54=83.2642436130123x_{54} = 83.2642436130123
x55=67.5590867686351x_{55} = 67.5590867686351
x56=23.6046454908472x_{56} = 23.6046454908472
x57=7.98178639820574x_{57} = 7.98178639820574
x58=51.8556353384249x_{58} = 51.8556353384249
x59=2.06334682805958x_{59} = 2.06334682805958
x60=92.6877950970258x_{60} = 92.6877950970258
x61=67.5589991681415x_{61} = -67.5589991681415
x62=20.4696471308323x_{62} = 20.4696471308323
x63=54.9961188799443x_{63} = 54.9961188799443
x64=20.4686968931616x_{64} = -20.4686968931616
x65=29.878364456351x_{65} = -29.878364456351
x66=42.4351733484599x_{66} = 42.4351733484599
x67=98.9702519153797x_{67} = -98.9702519153797

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
[98.9702927438931,)\left[98.9702927438931, \infty\right)
Convexa en los intervalos
(,98.9702519153797]\left(-\infty, -98.9702519153797\right]
Asíntotas horizontales
Hallemos las asíntotas horizontales mediante los límites de esta función con x->+oo y x->-oo
limx(((15x)cos(x)+5sin(x))+5)=,\lim_{x \to -\infty}\left(\left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5\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(((15x)cos(x)+5sin(x))+5)=,\lim_{x \to \infty}\left(\left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5\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 (1 - 5*x)*cos(x) + 5*sin(x) + 5, 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(((15x)cos(x)+5sin(x))+5x)y = x \lim_{x \to -\infty}\left(\frac{\left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5}{x}\right)
True

Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la derecha:
y=xlimx(((15x)cos(x)+5sin(x))+5x)y = x \lim_{x \to \infty}\left(\frac{\left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5}{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:
((15x)cos(x)+5sin(x))+5=(5x+1)cos(x)5sin(x)+5\left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5 = \left(5 x + 1\right) \cos{\left(x \right)} - 5 \sin{\left(x \right)} + 5
- No
((15x)cos(x)+5sin(x))+5=(5x+1)cos(x)+5sin(x)5\left(\left(1 - 5 x\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)}\right) + 5 = - \left(5 x + 1\right) \cos{\left(x \right)} + 5 \sin{\left(x \right)} - 5
- No
es decir, función
no es
par ni impar