Sr Examen

Gráfico de la función y = cox(x-1)

v

Gráfico:

interior superior

Puntos de intersección:

mostrar?

Definida a trozos:

Solución

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

Solución analítica
$$x_{1} = 1$$
$$x_{2} = - \frac{\pi}{2}$$
$$x_{3} = \frac{\pi}{2}$$
Solución numérica
$$x_{1} = -1.5707963267949$$
$$x_{2} = -64.4026493985908$$
$$x_{3} = 76.9690200129499$$
$$x_{4} = -23.5619449019235$$
$$x_{5} = -58.1194640914112$$
$$x_{6} = 61.261056745001$$
$$x_{7} = 80.1106126665397$$
$$x_{8} = -48.6946861306418$$
$$x_{9} = -29.845130209103$$
$$x_{10} = -4.71238898038469$$
$$x_{11} = -86.3937979737193$$
$$x_{12} = 1$$
$$x_{13} = -36.1283155162826$$
$$x_{14} = -98.9601685880785$$
$$x_{15} = 1.5707963267949$$
$$x_{16} = -39.2699081698724$$
$$x_{17} = 73.8274273593601$$
$$x_{18} = -92.6769832808989$$
$$x_{19} = 42.4115008234622$$
$$x_{20} = 67.5442420521806$$
$$x_{21} = -32.9867228626928$$
$$x_{22} = 14.1371669411541$$
$$x_{23} = 4.71238898038469$$
$$x_{24} = 32.9867228626928$$
$$x_{25} = -10.9955742875643$$
$$x_{26} = 70.6858347057703$$
$$x_{27} = 36.1283155162826$$
$$x_{28} = 20.4203522483337$$
$$x_{29} = -70.6858347057703$$
$$x_{30} = -26.7035375555132$$
$$x_{31} = 10.9955742875643$$
$$x_{32} = 23.5619449019235$$
$$x_{33} = 45.553093477052$$
$$x_{34} = 83.2522053201295$$
$$x_{35} = -67.5442420521806$$
$$x_{36} = -89.5353906273091$$
$$x_{37} = -54.9778714378214$$
$$x_{38} = 95.8185759344887$$
$$x_{39} = -17.2787595947439$$
$$x_{40} = 26.7035375555132$$
$$x_{41} = 17.2787595947439$$
$$x_{42} = -42.4115008234622$$
$$x_{43} = 54.9778714378214$$
$$x_{44} = -7.85398163397448$$
$$x_{45} = 48.6946861306418$$
$$x_{46} = -51.8362787842316$$
$$x_{47} = 89.5353906273091$$
$$x_{48} = 92.6769832808989$$
$$x_{49} = 58.1194640914112$$
$$x_{50} = -80.1106126665397$$
$$x_{51} = -73.8274273593601$$
$$x_{52} = 86.3937979737193$$
$$x_{53} = -76.9690200129499$$
$$x_{54} = 51.8362787842316$$
$$x_{55} = 39.2699081698724$$
$$x_{56} = -20.4203522483337$$
$$x_{57} = 64.4026493985908$$
$$x_{58} = -83.2522053201295$$
$$x_{59} = 98.9601685880785$$
$$x_{60} = 7.85398163397448$$
$$x_{61} = -95.8185759344887$$
$$x_{62} = -14.1371669411541$$
$$x_{63} = 29.845130209103$$
$$x_{64} = -45.553093477052$$
$$x_{65} = -61.261056745001$$
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 cos(x)*(x - 1).
$$\left(-1\right) \cos{\left(0 \right)}$$
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
$$- \left(x - 1\right) \sin{\left(x \right)} + \cos{\left(x \right)} = 0$$
Resolvermos esta ecuación
Raíces de esta ecuación
$$x_{1} = 50.2857695061759$$
$$x_{2} = 40.8657834053267$$
$$x_{3} = -15.7675317799203$$
$$x_{4} = 84.834929283594$$
$$x_{5} = -3.36671587754539$$
$$x_{6} = 81.6938008846843$$
$$x_{7} = -53.4254468020254$$
$$x_{8} = -0.567782020656099$$
$$x_{9} = -25.1709329794757$$
$$x_{10} = 91.1172831492274$$
$$x_{11} = -69.129296788477$$
$$x_{12} = 18.9053472009705$$
$$x_{13} = -109.964754502213$$
$$x_{14} = -34.5856130401369$$
$$x_{15} = 15.7755396389074$$
$$x_{16} = 3.51943605007227$$
$$x_{17} = 34.58728356964$$
$$x_{18} = 22.0386444078516$$
$$x_{19} = 65.9888317703628$$
$$x_{20} = -59.7067315662923$$
$$x_{21} = 59.7072924300783$$
$$x_{22} = 53.4261472496575$$
$$x_{23} = -40.8645864924056$$
$$x_{24} = 72.2706611309075$$
$$x_{25} = 12.6519831342203$$
$$x_{26} = -62.8475141081981$$
$$x_{27} = -56.5660373713478$$
$$x_{28} = -12.6395558422743$$
$$x_{29} = -84.8346514263999$$
$$x_{30} = 37.7263335361973$$
$$x_{31} = -65.9883725804509$$
$$x_{32} = 97.3997453605998$$
$$x_{33} = 87.9760912064584$$
$$x_{34} = -47.1446575542095$$
$$x_{35} = -81.693501252623$$
$$x_{36} = 75.4116616310224$$
$$x_{37} = 56.5666622243178$$
$$x_{38} = 62.8480203293155$$
$$x_{39} = -31.4467365238542$$
$$x_{40} = -91.1170422822337$$
$$x_{41} = 94.2585020796787$$
$$x_{42} = 78.5527100810745$$
$$x_{43} = -22.034534408764$$
$$x_{44} = 25.1740842709126$$
$$x_{45} = -75.411310006954$$
$$x_{46} = -78.5523860109268$$
$$x_{47} = -28.3084405150129$$
$$x_{48} = -87.9758328342401$$
$$x_{49} = 69.1297152082093$$
$$x_{50} = -97.399534561137$$
$$x_{51} = 31.4487567990639$$
$$x_{52} = 9.54132523092565$$
$$x_{53} = -37.7249292642936$$
$$x_{54} = 47.1455569712193$$
$$x_{55} = -100.540812853297$$
$$x_{56} = 44.0055457757373$$
$$x_{57} = -18.8997655344074$$
$$x_{58} = 6.46419193189059$$
$$x_{59} = -9.51955422261535$$
$$x_{60} = 100.541010687502$$
$$x_{61} = 28.3109329053961$$
$$x_{62} = -6.41719900457425$$
$$x_{63} = -72.270278284086$$
$$x_{64} = -556.063694810323$$
$$x_{65} = -94.2582769975219$$
$$x_{66} = 1.28924004659366$$
$$x_{67} = -50.2849788736454$$
$$x_{68} = -113.106099078316$$
$$x_{69} = -44.0045134880243$$
Signos de extremos en los puntos:
(50.28576950617588, 49.2756277212557)

(40.86578340532666, -39.8532472370851)

(-15.76753177992028, 16.7377915569281)

(84.83492928359397, -83.8289658187847)

(-3.3667158775453867, 4.25652882239464)

(81.69380088468426, 80.6876053354428)

(-53.425446802025405, 54.4162622483496)

(-0.5677820206560987, -1.32179043078767)

(-25.170932979475694, -26.151848709355)

(91.1172831492274, -90.1117353362952)

(-69.12929678847702, -70.1221681876335)

(18.905347200970496, 17.8774877381006)

(-109.96475450221315, 110.960248841392)

(-34.58561304013687, 35.5715707342139)

(15.77553963890737, -14.7418157375505)

(3.5194360500722652, -2.34172108723281)

(34.58728356963999, -33.5724068729686)

(22.03864440785156, -21.0149188120813)

(65.98883177036275, -64.9811395066923)

(-59.70673156629228, 60.6984969232027)

(59.70729243007827, -58.6987774534709)

(53.426147249657504, -52.416612625628)

(-40.864586492405614, 41.8526483322311)

(72.27066113090753, -71.2636466570958)

(12.651983134220295, 11.6093075837448)

(-62.84751410819813, -63.8396843902331)

(-56.566037371347775, -57.5573536597393)

(-12.639555842274314, -13.6030448832755)

(-84.83465142639987, 85.8288268660524)

(37.72633353619732, 36.7127268920407)

(-65.98837258045087, 66.9809098458042)

(97.39974536059977, -96.3945590434741)

(87.97609120645843, 86.9703430700788)

(-47.144657554209545, 48.1342755450787)

(-81.69350125262304, -82.6874554913451)

(75.41166163102243, 74.404943164129)

(56.566662224317795, 55.5576662083376)

(62.84802032931549, 61.8399375809263)

(-31.44673652385424, -32.4313376227909)

(-91.11704228223367, 92.1116148846623)

(94.2585020796787, 93.2531411005143)

(78.55271008107447, -77.5462636569844)

(-22.034534408764003, 23.0128585051561)

(25.174084270912637, 24.1534274712866)

(-75.41131000695397, -76.4047673134395)

(-78.55238601092682, 79.5461015890774)

(-28.308440515012887, 29.2913954640856)

(-87.97583283424012, -88.9702138631012)

(69.12971520820932, 68.1223774522407)

(-97.39953456113705, 98.3944536298525)

(31.448756799063855, 30.4323490392631)

(9.541325230925654, -8.4833813173875)

(-37.724929264293635, -38.7120241387053)

(47.1455569712193, -46.1347255066802)

(-100.5408128532973, -101.535889083058)

(44.00554577573732, 42.9939240808542)

(-18.89976553440737, -19.8746870972057)

(6.464191931890594, 5.37492331226648)

(-9.519554222615355, 10.4723434206105)

(100.54101068750202, 99.5359880123945)

(28.310932905396143, -27.2926436069057)

(-6.417199004574255, -7.35069340165152)

(-72.27027828408599, 73.2634551878583)

(-556.0636948103229, 557.062797249063)

(-94.25827699752193, -95.2530285435994)

(1.2892400465936646, 0.0803656318022444)

(-50.28497887364538, -51.2752322094434)

(-113.10609907831552, -114.10171744399)

(-44.0045134880243, -44.9934076035393)


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:
$$x_{1} = 40.8657834053267$$
$$x_{2} = 84.834929283594$$
$$x_{3} = -0.567782020656099$$
$$x_{4} = -25.1709329794757$$
$$x_{5} = 91.1172831492274$$
$$x_{6} = -69.129296788477$$
$$x_{7} = 15.7755396389074$$
$$x_{8} = 3.51943605007227$$
$$x_{9} = 34.58728356964$$
$$x_{10} = 22.0386444078516$$
$$x_{11} = 65.9888317703628$$
$$x_{12} = 59.7072924300783$$
$$x_{13} = 53.4261472496575$$
$$x_{14} = 72.2706611309075$$
$$x_{15} = -62.8475141081981$$
$$x_{16} = -56.5660373713478$$
$$x_{17} = -12.6395558422743$$
$$x_{18} = 97.3997453605998$$
$$x_{19} = -81.693501252623$$
$$x_{20} = -31.4467365238542$$
$$x_{21} = 78.5527100810745$$
$$x_{22} = -75.411310006954$$
$$x_{23} = -87.9758328342401$$
$$x_{24} = 9.54132523092565$$
$$x_{25} = -37.7249292642936$$
$$x_{26} = 47.1455569712193$$
$$x_{27} = -100.540812853297$$
$$x_{28} = -18.8997655344074$$
$$x_{29} = 28.3109329053961$$
$$x_{30} = -6.41719900457425$$
$$x_{31} = -94.2582769975219$$
$$x_{32} = -50.2849788736454$$
$$x_{33} = -113.106099078316$$
$$x_{34} = -44.0045134880243$$
Puntos máximos de la función:
$$x_{34} = 50.2857695061759$$
$$x_{34} = -15.7675317799203$$
$$x_{34} = -3.36671587754539$$
$$x_{34} = 81.6938008846843$$
$$x_{34} = -53.4254468020254$$
$$x_{34} = 18.9053472009705$$
$$x_{34} = -109.964754502213$$
$$x_{34} = -34.5856130401369$$
$$x_{34} = -59.7067315662923$$
$$x_{34} = -40.8645864924056$$
$$x_{34} = 12.6519831342203$$
$$x_{34} = -84.8346514263999$$
$$x_{34} = 37.7263335361973$$
$$x_{34} = -65.9883725804509$$
$$x_{34} = 87.9760912064584$$
$$x_{34} = -47.1446575542095$$
$$x_{34} = 75.4116616310224$$
$$x_{34} = 56.5666622243178$$
$$x_{34} = 62.8480203293155$$
$$x_{34} = -91.1170422822337$$
$$x_{34} = 94.2585020796787$$
$$x_{34} = -22.034534408764$$
$$x_{34} = 25.1740842709126$$
$$x_{34} = -78.5523860109268$$
$$x_{34} = -28.3084405150129$$
$$x_{34} = 69.1297152082093$$
$$x_{34} = -97.399534561137$$
$$x_{34} = 31.4487567990639$$
$$x_{34} = 44.0055457757373$$
$$x_{34} = 6.46419193189059$$
$$x_{34} = -9.51955422261535$$
$$x_{34} = 100.541010687502$$
$$x_{34} = -72.270278284086$$
$$x_{34} = -556.063694810323$$
$$x_{34} = 1.28924004659366$$
Decrece en los intervalos
$$\left[97.3997453605998, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -113.106099078316\right]$$
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
$$- (\left(x - 1\right) \cos{\left(x \right)} + 2 \sin{\left(x \right)}) = 0$$
Resolvermos esta ecuación
Raíces de esta ecuación
$$x_{1} = -5.03252136188435$$
$$x_{2} = -98.9801698872744$$
$$x_{3} = 17.4001107835996$$
$$x_{4} = 5.160488137379$$
$$x_{5} = 73.8548723024594$$
$$x_{6} = -8.07099262916911$$
$$x_{7} = 2.49855432221968$$
$$x_{8} = 70.7145152693381$$
$$x_{9} = 42.4597030690427$$
$$x_{10} = 11.1893928335334$$
$$x_{11} = 33.0490463971436$$
$$x_{12} = -92.6983251388017$$
$$x_{13} = -2.1381977537389$$
$$x_{14} = 89.5579708655131$$
$$x_{15} = 39.3220501388138$$
$$x_{16} = 0.325342230148932$$
$$x_{17} = 86.4172081819273$$
$$x_{18} = -89.5574724595818$$
$$x_{19} = -33.0454005126875$$
$$x_{20} = 51.8755701510007$$
$$x_{21} = -45.5959892966016$$
$$x_{22} = 29.914190397935$$
$$x_{23} = 23.6500166357864$$
$$x_{24} = 83.276508808943$$
$$x_{25} = 45.5979086029841$$
$$x_{26} = 76.9953313457533$$
$$x_{27} = -70.7137161464592$$
$$x_{28} = -64.4332054060865$$
$$x_{29} = 20.5224422884564$$
$$x_{30} = 58.1544427241882$$
$$x_{31} = -39.3194713707251$$
$$x_{32} = -95.83922578684$$
$$x_{33} = 95.839661033084$$
$$x_{34} = 61.2942152651978$$
$$x_{35} = 26.7809591256787$$
$$x_{36} = 98.9805779624548$$
$$x_{37} = 36.185096663082$$
$$x_{38} = -76.9946571767899$$
$$x_{39} = -86.4166729136966$$
$$x_{40} = -51.8740864721756$$
$$x_{41} = 55.0148813637847$$
$$x_{42} = -26.7754196064401$$
$$x_{43} = -29.9097446501775$$
$$x_{44} = -23.6429266008895$$
$$x_{45} = 92.6987903619905$$
$$x_{46} = 67.5742746536542$$
$$x_{47} = 14.2865731358648$$
$$x_{48} = -17.3871055208222$$
$$x_{49} = -80.1352578714972$$
$$x_{50} = 48.7365582531144$$
$$x_{51} = -20.5130526124428$$
$$x_{52} = -36.1820531210707$$
$$x_{53} = 8.12754793711753$$
$$x_{54} = -67.5733996147845$$
$$x_{55} = -73.8541396332586$$
$$x_{56} = -48.7348777037979$$
$$x_{57} = 80.135880273854$$
$$x_{58} = -83.2759324342754$$
$$x_{59} = 64.4341677074013$$
$$x_{60} = -61.2931519778376$$
$$x_{61} = -14.2674231119067$$
$$x_{62} = -11.1586068457488$$
$$x_{63} = -42.4574903585174$$
$$x_{64} = -58.1532616938786$$
$$x_{65} = -55.0135619144274$$

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
$$\left[95.839661033084, \infty\right)$$
Convexa en los intervalos
$$\left(-\infty, -95.83922578684\right]$$
Asíntotas horizontales
Hallemos las asíntotas horizontales mediante los límites de esta función con x->+oo y x->-oo
$$\lim_{x \to -\infty}\left(\left(x - 1\right) \cos{\left(x \right)}\right) = \left\langle -\infty, \infty\right\rangle$$
Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la izquierda:
$$y = \left\langle -\infty, \infty\right\rangle$$
$$\lim_{x \to \infty}\left(\left(x - 1\right) \cos{\left(x \right)}\right) = \left\langle -\infty, \infty\right\rangle$$
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 cos(x)*(x - 1), dividida por x con x->+oo y x ->-oo
$$\lim_{x \to -\infty}\left(\frac{\left(x - 1\right) \cos{\left(x \right)}}{x}\right) = \left\langle -1, 1\right\rangle$$
Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la izquierda:
$$y = \left\langle -1, 1\right\rangle x$$
$$\lim_{x \to \infty}\left(\frac{\left(x - 1\right) \cos{\left(x \right)}}{x}\right) = \left\langle -1, 1\right\rangle$$
Tomamos como el límite
es decir,
ecuación de la asíntota inclinada a la derecha:
$$y = \left\langle -1, 1\right\rangle x$$
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:
$$\left(x - 1\right) \cos{\left(x \right)} = \left(- x - 1\right) \cos{\left(x \right)}$$
- No
$$\left(x - 1\right) \cos{\left(x \right)} = - \left(- x - 1\right) \cos{\left(x \right)}$$
- No
es decir, función
no es
par ni impar