Sr Examen

Gráfico de la función y = (1-|x|)*(sin(x)+cos(x))

v

Gráfico:

interior superior

Puntos de intersección:

mostrar?

Definida a trozos:

Solución

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

Solución analítica
$$x_{1} = -1$$
$$x_{2} = 1$$
$$x_{3} = - \frac{\pi}{4}$$
Solución numérica
$$x_{1} = 21.2057504117311$$
$$x_{2} = 68.329640215578$$
$$x_{3} = 84.037603483527$$
$$x_{4} = 62.0464549083984$$
$$x_{5} = -63.6172512351933$$
$$x_{6} = -73.0420291959627$$
$$x_{7} = -35.3429173528852$$
$$x_{8} = -98.174770424681$$
$$x_{9} = -38.484510006475$$
$$x_{10} = -91.8915851175014$$
$$x_{11} = 1$$
$$x_{12} = 8.63937979737193$$
$$x_{13} = 74.6128255227576$$
$$x_{14} = -51.0508806208341$$
$$x_{15} = -10.2101761241668$$
$$x_{16} = 58.9048622548086$$
$$x_{17} = 5.49778714378214$$
$$x_{18} = 80.8960108299372$$
$$x_{19} = -0.785398163397448$$
$$x_{20} = -54.1924732744239$$
$$x_{21} = -85.6083998103219$$
$$x_{22} = 18.0641577581413$$
$$x_{23} = 93.4623814442964$$
$$x_{24} = -13.3517687777566$$
$$x_{25} = -47.9092879672443$$
$$x_{26} = 55.7632696012188$$
$$x_{27} = 46.3384916404494$$
$$x_{28} = 40.0553063332699$$
$$x_{29} = -79.3252145031423$$
$$x_{30} = -1$$
$$x_{31} = 33.7721210260903$$
$$x_{32} = -16.4933614313464$$
$$x_{33} = 11.7809724509617$$
$$x_{34} = -66.7588438887831$$
$$x_{35} = -57.3340659280137$$
$$x_{36} = 49.4800842940392$$
$$x_{37} = 65.1880475619882$$
$$x_{38} = 71.4712328691678$$
$$x_{39} = 96.6039740978861$$
$$x_{40} = -41.6261026600648$$
$$x_{41} = -29.0597320457056$$
$$x_{42} = -44.7676953136546$$
$$x_{43} = -22.776546738526$$
$$x_{44} = -69.9004365423729$$
$$x_{45} = 52.621676947629$$
$$x_{46} = -76.1836218495525$$
$$x_{47} = -25.9181393921158$$
$$x_{48} = 36.9137136796801$$
$$x_{49} = 30.6305283725005$$
$$x_{50} = 14.9225651045515$$
$$x_{51} = -19.6349540849362$$
$$x_{52} = 99.7455667514759$$
$$x_{53} = 2.35619449019234$$
$$x_{54} = 87.1791961371168$$
$$x_{55} = -82.4668071567321$$
$$x_{56} = -60.4756585816035$$
$$x_{57} = -3.92699081698724$$
$$x_{58} = -88.7499924639117$$
$$x_{59} = 90.3207887907066$$
$$x_{60} = -32.2013246992954$$
$$x_{61} = 43.1968989868597$$
$$x_{62} = -95.0331777710912$$
$$x_{63} = 77.7544181763474$$
$$x_{64} = 27.4889357189107$$
$$x_{65} = -7.06858347057703$$
$$x_{66} = 24.3473430653209$$
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 - |x|)*(sin(x) + cos(x)).
$$\left(1 - \left|{0}\right|\right) \left(\sin{\left(0 \right)} + \cos{\left(0 \right)}\right)$$
Resultado:
$$f{\left(0 \right)} = 1$$
Punto:
(0, 1)
Extremos de la función
Para hallar los extremos hay que resolver la ecuación
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
$$\frac{d}{d x} f{\left(x \right)} = $$
primera derivada
$$\left(1 - \left|{x}\right|\right) \left(- \sin{\left(x \right)} + \cos{\left(x \right)}\right) - \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right) \operatorname{sign}{\left(x \right)} = 0$$
Resolvermos esta ecuación
Raíces de esta ecuación
$$x_{1} = -52.6410389715955$$
$$x_{2} = 63.6332158480386$$
$$x_{3} = -55.7815219044393$$
$$x_{4} = -90.3319825222781$$
$$x_{5} = 47.930592805665$$
$$x_{6} = 16.5575505978831$$
$$x_{7} = 7.22779492037099$$
$$x_{8} = 25.9581849881156$$
$$x_{9} = -84.0496438924782$$
$$x_{10} = -65.2036217479876$$
$$x_{11} = 95.0438107123307$$
$$x_{12} = 57.3518097246237$$
$$x_{13} = -14.993903529302$$
$$x_{14} = -96.6144323887125$$
$$x_{15} = 69.9149461644257$$
$$x_{16} = 101.326330221322$$
$$x_{17} = -87.1907977832234$$
$$x_{18} = 19.6884121967352$$
$$x_{19} = -46.360533666053$$
$$x_{20} = 4.22745225886556$$
$$x_{21} = 38.5111624251243$$
$$x_{22} = -77.7674437949475$$
$$x_{23} = -2.85142429820486$$
$$x_{24} = -49.5006996323644$$
$$x_{25} = -5.70711911551724$$
$$x_{26} = 32.2333308441804$$
$$x_{27} = 85.6202167672022$$
$$x_{28} = 76.1969194828044$$
$$x_{29} = 35.3720025945026$$
$$x_{30} = -36.9415294709202$$
$$x_{31} = 10.3170963923239$$
$$x_{32} = -80.9085244861295$$
$$x_{33} = -58.9221250997238$$
$$x_{34} = -93.4731949673137$$
$$x_{35} = 41.6506975235482$$
$$x_{36} = -11.872687996638$$
$$x_{37} = 88.7613865036454$$
$$x_{38} = 1.7273485883332$$
$$x_{39} = -71.4854192487808$$
$$x_{40} = 73.0559064179207$$
$$x_{41} = 54.2112640758928$$
$$x_{42} = 66.7740462827018$$
$$x_{43} = -43.2205796912713$$
$$x_{44} = 91.9025854609873$$
$$x_{45} = -24.3900702302764$$
$$x_{46} = -62.0628300193565$$
$$x_{47} = 22.8223393046639$$
$$x_{48} = -40.0808887053963$$
$$x_{49} = 98.1850597089903$$
$$x_{50} = 13.4320333317738$$
$$x_{51} = 51.0708496663407$$
$$x_{52} = -68.344488149527$$
$$x_{53} = -74.6264067711121$$
$$x_{54} = -27.5266158623553$$
$$x_{55} = -8.76741839904067$$
$$x_{56} = 82.4790796296111$$
$$x_{57} = 79.3379790102328$$
$$x_{58} = -21.2550806871871$$
$$x_{59} = -33.8025969785559$$
$$x_{60} = 60.4924658499276$$
$$x_{61} = -99.755692403974$$
$$x_{62} = -30.664226249778$$
$$x_{63} = 29.0953101555357$$
$$x_{64} = 44.7905273343624$$
$$x_{65} = -18.1224941985499$$
Signos de extremos en los puntos:
(-52.641038971595464, 73.0177688087902)

(63.63321584803859, -88.5654558201357)

(-55.78152190443925, -77.4598667088465)

(-90.33198252227811, 126.326586486416)

(47.93059280566496, 66.3548188893407)

(16.557550597883104, 21.9563883732769)

(7.227794920370989, -8.69604098426168)

(25.958184988115615, -35.2679061100517)

(-84.04964389247817, 117.441419402457)

(-65.20362174798757, 90.7866211299255)

(95.04381071233067, -132.990514295959)

(57.3518097246237, -79.6809484638514)

(-14.993903529302022, 19.7400312325434)

(-96.6144323887125, 135.211832251379)

(69.91494616442574, -97.4501925637918)

(101.3263302213222, -141.875809319407)

(-87.19079778322345, -121.883992034234)

(19.688412196735236, -26.3916504024873)

(-46.36053366605297, 64.1338989964175)

(4.227452258865565, 4.35982591422769)

(38.51116242512435, -53.0299541140155)

(-77.76744379494752, 108.556350311417)

(-2.851424298204864, 2.30374441122779)

(-49.5006996323644, -68.5757725404651)

(-5.707119115517244, -6.51155187486998)

(32.23333084418042, -44.1479779755675)

(85.62021676720221, 119.662702838957)

(76.19691948280439, -106.335101227393)

(35.3720025945026, 48.5887931125945)

(-36.94152947092023, -50.8093360363574)

(10.317096392323908, 13.1011200766066)

(-80.90852448612954, -112.998871163687)

(-58.922125099723814, 81.902049718481)

(-93.47319496731373, -130.769200535834)

(41.650697523548196, 57.4713809462824)

(-11.872687996638032, -15.3116774034849)

(88.76138650364541, -124.10528667918)

(1.7273485883331952, -0.605050114497184)

(-71.48541924878079, 99.6714054071303)

(73.0559064179207, 101.892628214931)

(54.21126407589277, 75.2388061788205)

(66.77404628270185, 93.0077996244829)

(-43.22057969127131, -59.6921755364627)

(91.9025854609873, 128.547891188419)

(-24.39007023027635, -33.0483648574995)

(-62.06283001935652, -86.3443047119278)

(22.82233930466392, 30.8290962638108)

(-40.080888705396305, 55.2506383007215)

(98.18505970899032, 137.433154198728)

(13.432033331773757, -17.5249468665677)

(51.07084966634072, -70.7967567762686)

(-68.34448814952698, -95.2289903817816)

(-74.6264067711121, -104.113860349756)

(-27.526615862355346, 37.4876717930138)

(-8.767418399040672, 10.894869717293)

(82.47907962961114, -115.220142057668)

(79.33797901023276, 110.777607108399)

(-21.255080687187064, 28.6101634090838)

(-33.80259697855595, 46.3683361149338)

(60.49246584992765, 84.1231689294035)

(-99.75569240397398, -139.654479947574)

(-30.664226249778007, -41.9277343560368)

(29.095310155535664, 39.7076244064953)

(44.790527334362366, -61.9130164897839)

(-18.122494198549877, -24.1736719122665)


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:
$$x_{1} = 63.6332158480386$$
$$x_{2} = -55.7815219044393$$
$$x_{3} = 7.22779492037099$$
$$x_{4} = 25.9581849881156$$
$$x_{5} = 95.0438107123307$$
$$x_{6} = 57.3518097246237$$
$$x_{7} = 69.9149461644257$$
$$x_{8} = 101.326330221322$$
$$x_{9} = -87.1907977832234$$
$$x_{10} = 19.6884121967352$$
$$x_{11} = 38.5111624251243$$
$$x_{12} = -49.5006996323644$$
$$x_{13} = -5.70711911551724$$
$$x_{14} = 32.2333308441804$$
$$x_{15} = 76.1969194828044$$
$$x_{16} = -36.9415294709202$$
$$x_{17} = -80.9085244861295$$
$$x_{18} = -93.4731949673137$$
$$x_{19} = -11.872687996638$$
$$x_{20} = 88.7613865036454$$
$$x_{21} = 1.7273485883332$$
$$x_{22} = -43.2205796912713$$
$$x_{23} = -24.3900702302764$$
$$x_{24} = -62.0628300193565$$
$$x_{25} = 13.4320333317738$$
$$x_{26} = 51.0708496663407$$
$$x_{27} = -68.344488149527$$
$$x_{28} = -74.6264067711121$$
$$x_{29} = 82.4790796296111$$
$$x_{30} = -99.755692403974$$
$$x_{31} = -30.664226249778$$
$$x_{32} = 44.7905273343624$$
$$x_{33} = -18.1224941985499$$
Puntos máximos de la función:
$$x_{33} = -52.6410389715955$$
$$x_{33} = -90.3319825222781$$
$$x_{33} = 47.930592805665$$
$$x_{33} = 16.5575505978831$$
$$x_{33} = -84.0496438924782$$
$$x_{33} = -65.2036217479876$$
$$x_{33} = -14.993903529302$$
$$x_{33} = -96.6144323887125$$
$$x_{33} = -46.360533666053$$
$$x_{33} = 4.22745225886556$$
$$x_{33} = -77.7674437949475$$
$$x_{33} = -2.85142429820486$$
$$x_{33} = 85.6202167672022$$
$$x_{33} = 35.3720025945026$$
$$x_{33} = 10.3170963923239$$
$$x_{33} = -58.9221250997238$$
$$x_{33} = 41.6506975235482$$
$$x_{33} = -71.4854192487808$$
$$x_{33} = 73.0559064179207$$
$$x_{33} = 54.2112640758928$$
$$x_{33} = 66.7740462827018$$
$$x_{33} = 91.9025854609873$$
$$x_{33} = 22.8223393046639$$
$$x_{33} = -40.0808887053963$$
$$x_{33} = 98.1850597089903$$
$$x_{33} = -27.5266158623553$$
$$x_{33} = -8.76741839904067$$
$$x_{33} = 79.3379790102328$$
$$x_{33} = -21.2550806871871$$
$$x_{33} = -33.8025969785559$$
$$x_{33} = 60.4924658499276$$
$$x_{33} = 29.0953101555357$$
Decrece en los intervalos
$$\left[101.326330221322, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -99.755692403974\right]$$
Puntos de flexiones
Hallemos los puntos de flexiones, para eso hay que resolver la ecuación
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(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:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
segunda derivada
$$2 \left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) \operatorname{sign}{\left(x \right)} + \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right) \left(\left|{x}\right| - 1\right) - 2 \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right) \delta\left(x\right) = 0$$
Resolvermos esta ecuación
Soluciones no halladas,
tal vez la función no tenga flexiones
Asíntotas horizontales
Hallemos las asíntotas horizontales mediante los límites de esta función con x->+oo y x->-oo
$$\lim_{x \to -\infty}\left(\left(1 - \left|{x}\right|\right) \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right)\right) = \left\langle -\infty, \infty\right\rangle$$
Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la izquierda:
$$y = \left\langle -\infty, \infty\right\rangle$$
$$\lim_{x \to \infty}\left(\left(1 - \left|{x}\right|\right) \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right)\right) = \left\langle -\infty, \infty\right\rangle$$
Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la derecha:
$$y = \left\langle -\infty, \infty\right\rangle$$
Asíntotas inclinadas
Se puede hallar la asíntota inclinada calculando el límite de la función (1 - |x|)*(sin(x) + cos(x)), dividida por x con x->+oo y x ->-oo
$$\lim_{x \to -\infty}\left(\frac{\left(1 - \left|{x}\right|\right) \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right)}{x}\right) = \left\langle -2, 2\right\rangle$$
Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la izquierda:
$$y = \left\langle -2, 2\right\rangle x$$
$$\lim_{x \to \infty}\left(\frac{\left(1 - \left|{x}\right|\right) \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right)}{x}\right) = \left\langle -2, 2\right\rangle$$
Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la derecha:
$$y = \left\langle -2, 2\right\rangle x$$
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:
$$\left(1 - \left|{x}\right|\right) \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right) = \left(1 - \left|{x}\right|\right) \left(- \sin{\left(x \right)} + \cos{\left(x \right)}\right)$$
- No
$$\left(1 - \left|{x}\right|\right) \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right) = - \left(1 - \left|{x}\right|\right) \left(- \sin{\left(x \right)} + \cos{\left(x \right)}\right)$$
- No
es decir, función
no es
par ni impar
Gráfico
Gráfico de la función y = (1-|x|)*(sin(x)+cos(x))