Sr Examen

Gráfico de la función y = x=3(cost+tsint)

v

Gráfico:

interior superior

Puntos de intersección:

mostrar?

Definida a trozos:

Solución

Ha introducido [src]
f(t) = 3*(cos(t) + t*sin(t))
f(t)=3(tsin(t)+cos(t))f{\left(t \right)} = 3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right)
f = 3*(t*sin(t) + cos(t))
Gráfico de la función
02468-8-6-4-2-1010-5050
Puntos de cruce con el eje de coordenadas X
El gráfico de la función cruce el eje T con f = 0
o sea hay que resolver la ecuación:
3(tsin(t)+cos(t))=03 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right) = 0
Resolvermos esta ecuación
Puntos de cruce con el eje T:

Solución numérica
t1=69.100567727981t_{1} = -69.100567727981
t2=12.4864543952238t_{2} = -12.4864543952238
t3=81.6691650818489t_{3} = 81.6691650818489
t4=2.79838604578389t_{4} = -2.79838604578389
t5=91.0952098694071t_{5} = 91.0952098694071
t6=78.5270825679419t_{6} = 78.5270825679419
t7=72.2427897046973t_{7} = -72.2427897046973
t8=15.644128370333t_{8} = 15.644128370333
t9=43.9595528888955t_{9} = -43.9595528888955
t10=50.2455828375744t_{10} = 50.2455828375744
t11=62.8159348889734t_{11} = -62.8159348889734
t12=6.12125046689807t_{12} = 6.12125046689807
t13=84.811211299318t_{13} = -84.811211299318
t14=62.8159348889734t_{14} = 62.8159348889734
t15=56.5309801938186t_{15} = 56.5309801938186
t16=28.2389365752603t_{16} = -28.2389365752603
t17=56.5309801938186t_{17} = -56.5309801938186
t18=25.0929104121121t_{18} = -25.0929104121121
t19=59.6735041304405t_{19} = -59.6735041304405
t20=69.100567727981t_{20} = 69.100567727981
t21=47.1026627703624t_{21} = -47.1026627703624
t22=72.2427897046973t_{22} = 72.2427897046973
t23=40.8162093266346t_{23} = -40.8162093266346
t24=47.1026627703624t_{24} = 47.1026627703624
t25=78.5270825679419t_{25} = -78.5270825679419
t26=97.3791034786112t_{26} = 97.3791034786112
t27=31.3840740178899t_{27} = -31.3840740178899
t28=37.672573565113t_{28} = -37.672573565113
t29=18.7964043662102t_{29} = 18.7964043662102
t30=75.3849592185347t_{30} = -75.3849592185347
t31=40.8162093266346t_{31} = 40.8162093266346
t32=34.5285657554621t_{32} = -34.5285657554621
t33=53.3883466217256t_{33} = -53.3883466217256
t34=34.5285657554621t_{34} = 34.5285657554621
t35=37.672573565113t_{35} = 37.672573565113
t36=100.521017074687t_{36} = -100.521017074687
t37=6.12125046689807t_{37} = -6.12125046689807
t38=65.9582857893902t_{38} = -65.9582857893902
t39=59.6735041304405t_{39} = 59.6735041304405
t40=91.0952098694071t_{40} = -91.0952098694071
t41=75.3849592185347t_{41} = 75.3849592185347
t42=65.9582857893902t_{42} = 65.9582857893902
t43=84.811211299318t_{43} = 84.811211299318
t44=87.9532251106725t_{44} = -87.9532251106725
t45=100.521017074687t_{45} = 100.521017074687
t46=25.0929104121121t_{46} = 25.0929104121121
t47=94.2371684817036t_{47} = 94.2371684817036
t48=94.2371684817036t_{48} = -94.2371684817036
t49=2.79838604578389t_{49} = 2.79838604578389
t50=28.2389365752603t_{50} = 28.2389365752603
t51=21.945612879981t_{51} = -21.945612879981
t52=53.3883466217256t_{52} = 53.3883466217256
t53=9.31786646179107t_{53} = 9.31786646179107
t54=50.2455828375744t_{54} = -50.2455828375744
t55=43.9595528888955t_{55} = 43.9595528888955
t56=18.7964043662102t_{56} = -18.7964043662102
t57=81.6691650818489t_{57} = -81.6691650818489
t58=9.31786646179107t_{58} = -9.31786646179107
t59=113.088493127061t_{59} = -113.088493127061
t60=87.9532251106725t_{60} = 87.9532251106725
t61=12.4864543952238t_{61} = 12.4864543952238
t62=97.3791034786112t_{62} = -97.3791034786112
t63=31.3840740178899t_{63} = 31.3840740178899
t64=15.644128370333t_{64} = -15.644128370333
t65=21.945612879981t_{65} = 21.945612879981
Puntos de cruce con el eje de coordenadas Y
El gráfico cruce el eje Y cuando t es igual a 0:
sustituimos t = 0 en 3*(cos(t) + t*sin(t)).
3(0sin(0)+cos(0))3 \left(0 \sin{\left(0 \right)} + \cos{\left(0 \right)}\right)
Resultado:
f(0)=3f{\left(0 \right)} = 3
Punto:
(0, 3)
Extremos de la función
Para hallar los extremos hay que resolver la ecuación
ddtf(t)=0\frac{d}{d t} f{\left(t \right)} = 0
(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
ddtf(t)=\frac{d}{d t} f{\left(t \right)} =
primera derivada
3tcos(t)=03 t \cos{\left(t \right)} = 0
Resolvermos esta ecuación
Raíces de esta ecuación
t1=0t_{1} = 0
t2=π2t_{2} = - \frac{\pi}{2}
t3=π2t_{3} = \frac{\pi}{2}
Signos de extremos en los puntos:
(0, 3)

 -pi   3*pi 
(----, ----)
  2     2   

 pi  3*pi 
(--, ----)
 2    2   


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:
t1=0t_{1} = 0
Puntos máximos de la función:
t1=π2t_{1} = - \frac{\pi}{2}
t1=π2t_{1} = \frac{\pi}{2}
Decrece en los intervalos
(,π2][0,)\left(-\infty, - \frac{\pi}{2}\right] \cup \left[0, \infty\right)
Crece en los intervalos
(,0][π2,)\left(-\infty, 0\right] \cup \left[\frac{\pi}{2}, \infty\right)
Puntos de flexiones
Hallemos los puntos de flexiones, para eso hay que resolver la ecuación
d2dt2f(t)=0\frac{d^{2}}{d t^{2}} f{\left(t \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:
d2dt2f(t)=\frac{d^{2}}{d t^{2}} f{\left(t \right)} =
segunda derivada
3(tsin(t)+cos(t))=03 \left(- t \sin{\left(t \right)} + \cos{\left(t \right)}\right) = 0
Resolvermos esta ecuación
Raíces de esta ecuación
t1=59.7070073053355t_{1} = 59.7070073053355
t2=25.1724463266467t_{2} = -25.1724463266467
t3=31.4477146375462t_{3} = 31.4477146375462
t4=97.3996388790738t_{4} = 97.3996388790738
t5=56.5663442798215t_{5} = -56.5663442798215
t6=47.145097736761t_{6} = -47.145097736761
t7=18.90240995686t_{7} = 18.90240995686
t8=44.0050179208308t_{8} = 44.0050179208308
t9=56.5663442798215t_{9} = 56.5663442798215
t10=28.309642854452t_{10} = -28.309642854452
t11=147.661626855354t_{11} = -147.661626855354
t12=81.6936492356017t_{12} = -81.6936492356017
t13=91.1171613944647t_{13} = -91.1171613944647
t14=12.6452872238566t_{14} = -12.6452872238566
t15=72.270467060309t_{15} = 72.270467060309
t16=6.43729817917195t_{16} = 6.43729817917195
t17=65.9885986984904t_{17} = 65.9885986984904
t18=34.5864242152889t_{18} = -34.5864242152889
t19=37.7256128277765t_{19} = 37.7256128277765
t20=40.8651703304881t_{20} = -40.8651703304881
t21=78.5525459842429t_{21} = 78.5525459842429
t22=9.52933440536196t_{22} = -9.52933440536196
t23=22.0364967279386t_{23} = 22.0364967279386
t24=59.7070073053355t_{24} = -59.7070073053355
t25=100.540910786842t_{25} = -100.540910786842
t26=15.7712848748159t_{26} = 15.7712848748159
t27=84.8347887180423t_{27} = -84.8347887180423
t28=75.4114834888481t_{28} = 75.4114834888481
t29=3.42561845948173t_{29} = 3.42561845948173
t30=28.309642854452t_{30} = 28.309642854452
t31=94.2583883450399t_{31} = 94.2583883450399
t32=100.540910786842t_{32} = 100.540910786842
t33=69.1295029738953t_{33} = -69.1295029738953
t34=44.0050179208308t_{34} = -44.0050179208308
t35=9.52933440536196t_{35} = 9.52933440536196
t36=18.90240995686t_{36} = -18.90240995686
t37=12.6452872238566t_{37} = 12.6452872238566
t38=34.5864242152889t_{38} = 34.5864242152889
t39=116.247530303932t_{39} = -116.247530303932
t40=81.6936492356017t_{40} = 81.6936492356017
t41=22.0364967279386t_{41} = -22.0364967279386
t42=69.1295029738953t_{42} = 69.1295029738953
t43=72.270467060309t_{43} = -72.270467060309
t44=37.7256128277765t_{44} = -37.7256128277765
t45=84.8347887180423t_{45} = 84.8347887180423
t46=0.86033358901938t_{46} = 0.86033358901938
t47=78.5525459842429t_{47} = -78.5525459842429
t48=87.9759605524932t_{48} = -87.9759605524932
t49=75.4114834888481t_{49} = -75.4114834888481
t50=53.4257904773947t_{50} = 53.4257904773947
t51=65.9885986984904t_{51} = -65.9885986984904
t52=97.3996388790738t_{52} = -97.3996388790738
t53=6.43729817917195t_{53} = -6.43729817917195
t54=31.4477146375462t_{54} = -31.4477146375462
t55=47.145097736761t_{55} = 47.145097736761
t56=25.1724463266467t_{56} = 25.1724463266467
t57=62.8477631944545t_{57} = 62.8477631944545
t58=62.8477631944545t_{58} = -62.8477631944545
t59=0.86033358901938t_{59} = -0.86033358901938
t60=50.2853663377737t_{60} = 50.2853663377737
t61=91.1171613944647t_{61} = 91.1171613944647
t62=3.42561845948173t_{62} = -3.42561845948173
t63=40.8651703304881t_{63} = 40.8651703304881
t64=87.9759605524932t_{64} = 87.9759605524932
t65=53.4257904773947t_{65} = -53.4257904773947
t66=15.7712848748159t_{66} = -15.7712848748159
t67=94.2583883450399t_{67} = -94.2583883450399
t68=50.2853663377737t_{68} = -50.2853663377737

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
[97.3996388790738,)\left[97.3996388790738, \infty\right)
Convexa en los intervalos
(,100.540910786842]\left(-\infty, -100.540910786842\right]
Asíntotas horizontales
Hallemos las asíntotas horizontales mediante los límites de esta función con t->+oo y t->-oo
True

Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la izquierda:
y=limt(3(tsin(t)+cos(t)))y = \lim_{t \to -\infty}\left(3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right)\right)
True

Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la derecha:
y=limt(3(tsin(t)+cos(t)))y = \lim_{t \to \infty}\left(3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right)\right)
Asíntotas inclinadas
Se puede hallar la asíntota inclinada calculando el límite de la función 3*(cos(t) + t*sin(t)), dividida por t con t->+oo y t ->-oo
True

Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la izquierda:
y=tlimt(3(tsin(t)+cos(t))t)y = t \lim_{t \to -\infty}\left(\frac{3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right)}{t}\right)
True

Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la derecha:
y=tlimt(3(tsin(t)+cos(t))t)y = t \lim_{t \to \infty}\left(\frac{3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right)}{t}\right)
Paridad e imparidad de la función
Comprobemos si la función es par o impar mediante las relaciones f = f(-t) и f = -f(-t).
Pues, comprobamos:
3(tsin(t)+cos(t))=3(tsin(t)+cos(t))3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right) = 3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right)
- Sí
3(tsin(t)+cos(t))=3(tsin(t)+cos(t))3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right) = - 3 \left(t \sin{\left(t \right)} + \cos{\left(t \right)}\right)
- No
es decir, función
es
par