Sr Examen

Gráfico de la función y = x^sin(pi*x)

v

Gráfico:

interior superior

Puntos de intersección:

mostrar?

Definida a trozos:

Solución

Ha introducido [src]
        sin(pi*x)
f(x) = x         
f(x)=xsin(πx)f{\left(x \right)} = x^{\sin{\left(\pi x \right)}}
f = x^sin(pi*x)
Gráfico de la función
02468-8-6-4-2-1010010
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:
xsin(πx)=0x^{\sin{\left(\pi x \right)}} = 0
Resolvermos esta ecuación
Solución no hallada,
puede ser que el gráfico no cruce el eje X
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 x^sin(pi*x).
0sin(0π)0^{\sin{\left(0 \pi \right)}}
Resultado:
f(0)=1f{\left(0 \right)} = 1
Punto:
(0, 1)
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
xsin(πx)(πlog(x)cos(πx)+sin(πx)x)=0x^{\sin{\left(\pi x \right)}} \left(\pi \log{\left(x \right)} \cos{\left(\pi x \right)} + \frac{\sin{\left(\pi x \right)}}{x}\right) = 0
Resolvermos esta ecuación
Raíces de esta ecuación
x1=19.5017490094545x_{1} = 19.5017490094545
x2=57.5004348922392x_{2} = 57.5004348922392
x3=45.5005832814248x_{3} = 45.5005832814248
x4=25.5012267688739x_{4} = 25.5012267688739
x5=41.5006552933046x_{5} = 41.5006552933046
x6=15.5023844354396x_{6} = 15.5023844354396
x7=77.5003005241291x_{7} = 77.5003005241291
x8=81.5002825065307x_{8} = 81.5002825065307
x9=23.5013655948116x_{9} = 23.5013655948116
x10=87.500258954712x_{10} = 87.500258954712
x11=29.5010147918644x_{11} = 29.5010147918644
x12=39.500697720819x_{12} = 39.500697720819
x13=95.5002327093841x_{13} = 95.5002327093841
x14=89.5002518949765x_{14} = 89.5002518949765
x15=51.500499133648x_{15} = 51.500499133648
x16=83.5002742292025x_{16} = 83.5002742292025
x17=85.5002663895521x_{17} = 85.5002663895521
x18=69.5003437248215x_{18} = 69.5003437248215
x19=37.5007454665031x_{19} = 37.5007454665031
x20=75.5003103501492x_{20} = 75.5003103501492
x21=31.5009322971412x_{21} = 31.5009322971412
x22=91.5002451834337x_{22} = 91.5002451834337
x23=13.5028827293393x_{23} = 13.5028827293393
x24=27.5011116448589x_{24} = 27.5011116448589
x25=71.5003318902279x_{25} = 71.5003318902279
x26=61.5003999684073x_{26} = 61.5003999684073
x27=33.5008612748194x_{27} = 33.5008612748194
x28=3.52280102016443x_{28} = 3.52280102016443
x29=9.50473369645658x_{29} = 9.50473369645658
x30=21.5015358699427x_{30} = 21.5015358699427
x31=93.5002387956481x_{31} = 93.5002387956481
x32=73.500320786611x_{32} = 73.500320786611
x33=65.5003698847997x_{33} = 65.5003698847997
x34=11.503605658404x_{34} = 11.503605658404
x35=63.5003843847485x_{35} = 63.5003843847485
x36=53.5004758751014x_{36} = 53.5004758751014
x37=5.51076872035014x_{37} = 5.51076872035014
x38=67.5003563624568x_{38} = 67.5003563624568
x39=79.5002912579924x_{39} = 79.5002912579924
x40=59.5004167574861x_{40} = 59.5004167574861
x41=47.5005524976704x_{41} = 47.5005524976704
x42=1.62257359090008x_{42} = 1.62257359090008
x43=17.5020224999823x_{43} = 17.5020224999823
x44=97.500226904367x_{44} = 97.500226904367
x45=7.50669485268483x_{45} = 7.50669485268483
x46=55.500454535085x_{46} = 55.500454535085
x47=35.5007995527148x_{47} = 35.5007995527148
x48=49.5005245714587x_{48} = 49.5005245714587
x49=43.5006173669394x_{49} = 43.5006173669394
x50=99.5002213620728x_{50} = 99.5002213620728
Signos de extremos en los puntos:
                                     sin(1.50174900945455*pi) 
(19.501749009454546, 19.5017490094545                        )

                                     sin(1.50043489223918*pi) 
(57.500434892239184, 57.5004348922392                        )

                                   sin(1.5005832814248*pi) 
(45.5005832814248, 45.5005832814248                       )

                                     sin(1.50122676887392*pi) 
(25.501226768873916, 25.5012267688739                        )

                                    sin(1.50065529330456*pi) 
(41.50065529330456, 41.5006552933046                        )

                                   sin(1.5023844354396*pi) 
(15.5023844354396, 15.5023844354396                       )

                                    sin(1.50030052412909*pi) 
(77.50030052412909, 77.5003005241291                        )

                                   sin(1.5002825065307*pi) 
(81.5002825065307, 81.5002825065307                       )

                                    sin(1.50136559481162*pi) 
(23.50136559481162, 23.5013655948116                        )

                                   sin(1.50025895471195*pi) 
(87.50025895471195, 87.500258954712                        )

                                     sin(1.50101479186437*pi) 
(29.501014791864375, 29.5010147918644                        )

                                   sin(1.50069772081905*pi) 
(39.50069772081905, 39.500697720819                        )

                                    sin(1.50023270938412*pi) 
(95.50023270938412, 95.5002327093841                        )

                                    sin(1.50025189497646*pi) 
(89.50025189497646, 89.5002518949765                        )

                                    sin(1.50049913364796*pi) 
(51.500499133647956, 51.500499133648                        )

                                   sin(1.5002742292025*pi) 
(83.5002742292025, 83.5002742292025                       )

                                    sin(1.50026638955205*pi) 
(85.50026638955205, 85.5002663895521                        )

                                    sin(1.50034372482146*pi) 
(69.50034372482146, 69.5003437248215                        )

                                    sin(1.50074546650314*pi) 
(37.50074546650314, 37.5007454665031                        )

                                    sin(1.50031035014919*pi) 
(75.50031035014919, 75.5003103501492                        )

                                     sin(1.50093229714118*pi) 
(31.500932297141183, 31.5009322971412                        )

                                    sin(1.50024518343373*pi) 
(91.50024518343373, 91.5002451834337                        )

                                    sin(1.50288272933928*pi) 
(13.50288272933928, 13.5028827293393                        )

                                    sin(1.50111164485893*pi) 
(27.50111164485893, 27.5011116448589                        )

                                   sin(1.5003318902279*pi) 
(71.5003318902279, 71.5003318902279                       )

                                    sin(1.50039996840725*pi) 
(61.50039996840725, 61.5003999684073                        )

                                    sin(1.50086127481938*pi) 
(33.50086127481938, 33.5008612748194                        )

                                    sin(1.52280102016443*pi) 
(3.522801020164427, 3.52280102016443                        )

                                    sin(1.50473369645658*pi) 
(9.504733696456576, 9.50473369645658                        )

                                   sin(1.5015358699427*pi) 
(21.5015358699427, 21.5015358699427                       )

                                    sin(1.50023879564809*pi) 
(93.50023879564809, 93.5002387956481                        )

                                   sin(1.50032078661104*pi) 
(73.50032078661104, 73.500320786611                        )

                                    sin(1.50036988479974*pi) 
(65.50036988479974, 65.5003698847997                        )

                                    sin(1.50360565840399*pi) 
(11.503605658403993, 11.503605658404                        )

                                     sin(1.50038438474849*pi) 
(63.500384384748486, 63.5003843847485                        )

                                    sin(1.50047587510142*pi) 
(53.50047587510142, 53.5004758751014                        )

                                   sin(1.51076872035014*pi) 
(5.51076872035014, 5.51076872035014                        )

                                    sin(1.50035636245683*pi) 
(67.50035636245683, 67.5003563624568                        )

                                    sin(1.50029125799242*pi) 
(79.50029125799242, 79.5002912579924                        )

                                    sin(1.50041675748614*pi) 
(59.50041675748614, 59.5004167574861                        )

                                    sin(1.50055249767036*pi) 
(47.50055249767036, 47.5005524976704                        )

                                     sin(1.62257359090008*pi) 
(1.6225735909000836, 1.62257359090008                        )

                                     sin(1.50202249998232*pi) 
(17.502022499982317, 17.5020224999823                        )

                                   sin(1.50022690436695*pi) 
(97.50022690436695, 97.500226904367                        )

                                    sin(1.50669485268483*pi) 
(7.506694852684833, 7.50669485268483                        )

                                   sin(1.50045453508502*pi) 
(55.50045453508502, 55.500454535085                        )

                                    sin(1.50079955271479*pi) 
(35.50079955271479, 35.5007995527148                        )

                                    sin(1.50052457145874*pi) 
(49.50052457145874, 49.5005245714587                        )

                                    sin(1.50061736693939*pi) 
(43.50061736693939, 43.5006173669394                        )

                                    sin(1.50022136207275*pi) 
(99.50022136207275, 99.5002213620728                        )


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=19.5017490094545x_{1} = 19.5017490094545
x2=57.5004348922392x_{2} = 57.5004348922392
x3=45.5005832814248x_{3} = 45.5005832814248
x4=25.5012267688739x_{4} = 25.5012267688739
x5=41.5006552933046x_{5} = 41.5006552933046
x6=15.5023844354396x_{6} = 15.5023844354396
x7=77.5003005241291x_{7} = 77.5003005241291
x8=81.5002825065307x_{8} = 81.5002825065307
x9=23.5013655948116x_{9} = 23.5013655948116
x10=87.500258954712x_{10} = 87.500258954712
x11=29.5010147918644x_{11} = 29.5010147918644
x12=39.500697720819x_{12} = 39.500697720819
x13=95.5002327093841x_{13} = 95.5002327093841
x14=89.5002518949765x_{14} = 89.5002518949765
x15=51.500499133648x_{15} = 51.500499133648
x16=83.5002742292025x_{16} = 83.5002742292025
x17=85.5002663895521x_{17} = 85.5002663895521
x18=69.5003437248215x_{18} = 69.5003437248215
x19=37.5007454665031x_{19} = 37.5007454665031
x20=75.5003103501492x_{20} = 75.5003103501492
x21=31.5009322971412x_{21} = 31.5009322971412
x22=91.5002451834337x_{22} = 91.5002451834337
x23=13.5028827293393x_{23} = 13.5028827293393
x24=27.5011116448589x_{24} = 27.5011116448589
x25=71.5003318902279x_{25} = 71.5003318902279
x26=61.5003999684073x_{26} = 61.5003999684073
x27=33.5008612748194x_{27} = 33.5008612748194
x28=3.52280102016443x_{28} = 3.52280102016443
x29=9.50473369645658x_{29} = 9.50473369645658
x30=21.5015358699427x_{30} = 21.5015358699427
x31=93.5002387956481x_{31} = 93.5002387956481
x32=73.500320786611x_{32} = 73.500320786611
x33=65.5003698847997x_{33} = 65.5003698847997
x34=11.503605658404x_{34} = 11.503605658404
x35=63.5003843847485x_{35} = 63.5003843847485
x36=53.5004758751014x_{36} = 53.5004758751014
x37=5.51076872035014x_{37} = 5.51076872035014
x38=67.5003563624568x_{38} = 67.5003563624568
x39=79.5002912579924x_{39} = 79.5002912579924
x40=59.5004167574861x_{40} = 59.5004167574861
x41=47.5005524976704x_{41} = 47.5005524976704
x42=1.62257359090008x_{42} = 1.62257359090008
x43=17.5020224999823x_{43} = 17.5020224999823
x44=97.500226904367x_{44} = 97.500226904367
x45=7.50669485268483x_{45} = 7.50669485268483
x46=55.500454535085x_{46} = 55.500454535085
x47=35.5007995527148x_{47} = 35.5007995527148
x48=49.5005245714587x_{48} = 49.5005245714587
x49=43.5006173669394x_{49} = 43.5006173669394
x50=99.5002213620728x_{50} = 99.5002213620728
La función no tiene puntos máximos
Decrece en los intervalos
[99.5002213620728,)\left[99.5002213620728, \infty\right)
Crece en los intervalos
(,1.62257359090008]\left(-\infty, 1.62257359090008\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
xsin(πx)((πlog(x)cos(πx)+sin(πx)x)2π2log(x)sin(πx)+2πcos(πx)xsin(πx)x2)=0x^{\sin{\left(\pi x \right)}} \left(\left(\pi \log{\left(x \right)} \cos{\left(\pi x \right)} + \frac{\sin{\left(\pi x \right)}}{x}\right)^{2} - \pi^{2} \log{\left(x \right)} \sin{\left(\pi x \right)} + \frac{2 \pi \cos{\left(\pi x \right)}}{x} - \frac{\sin{\left(\pi x \right)}}{x^{2}}\right) = 0
Resolvermos esta ecuación
Raíces de esta ecuación
x1=2.26452144556189x_{1} = 2.26452144556189
x2=6.28781709665755x_{2} = 6.28781709665755
x3=0.680301458874261x_{3} = 0.680301458874261
x4=4.27379180906125x_{4} = 4.27379180906125

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
(,0.680301458874261]\left(-\infty, 0.680301458874261\right]
Convexa en los intervalos
[6.28781709665755,)\left[6.28781709665755, \infty\right)
Asíntotas horizontales
Hallemos las asíntotas horizontales mediante los límites de esta función con x->+oo y x->-oo
limxxsin(πx)=()1,1\lim_{x \to -\infty} x^{\sin{\left(\pi x \right)}} = \left(-\infty\right)^{\left\langle -1, 1\right\rangle}
Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la izquierda:
y=()1,1y = \left(-\infty\right)^{\left\langle -1, 1\right\rangle}
limxxsin(πx)=1,1\lim_{x \to \infty} x^{\sin{\left(\pi x \right)}} = \infty^{\left\langle -1, 1\right\rangle}
Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la derecha:
y=1,1y = \infty^{\left\langle -1, 1\right\rangle}
Asíntotas inclinadas
Se puede hallar la asíntota inclinada calculando el límite de la función x^sin(pi*x), dividida por x con x->+oo y x ->-oo
limx(xsin(πx)x)=0\lim_{x \to -\infty}\left(\frac{x^{\sin{\left(\pi x \right)}}}{x}\right) = 0
Tomamos como el límite
es decir,
la inclinada coincide con la asíntota horizontal a la derecha
True

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