Sr Examen

Gráfico de la función y = (sinx*cosx)/(sinx+cosx)

v

Gráfico:

interior superior

Puntos de intersección:

mostrar?

Definida a trozos:

Solución

Ha introducido [src]
        sin(x)*cos(x) 
f(x) = ---------------
       sin(x) + cos(x)
f(x)=sin(x)cos(x)sin(x)+cos(x)f{\left(x \right)} = \frac{\sin{\left(x \right)} \cos{\left(x \right)}}{\sin{\left(x \right)} + \cos{\left(x \right)}}
f = (sin(x)*cos(x))/(sin(x) + cos(x))
Gráfico de la función
02468-8-6-4-2-1010-100100
Dominio de definición de la función
Puntos en los que la función no está definida exactamente:
x1=0.785398163397448x_{1} = -0.785398163397448
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:
sin(x)cos(x)sin(x)+cos(x)=0\frac{\sin{\left(x \right)} \cos{\left(x \right)}}{\sin{\left(x \right)} + \cos{\left(x \right)}} = 0
Resolvermos esta ecuación
Puntos de cruce con el eje X:

Solución analítica
x1=0x_{1} = 0
x2=π2x_{2} = - \frac{\pi}{2}
x3=π2x_{3} = \frac{\pi}{2}
Solución numérica
x1=59.6902604182061x_{1} = -59.6902604182061
x2=7.85398163397448x_{2} = 7.85398163397448
x3=21.9911485751286x_{3} = -21.9911485751286
x4=75.398223686155x_{4} = -75.398223686155
x5=50.2654824574367x_{5} = 50.2654824574367
x6=95.8185759344887x_{6} = 95.8185759344887
x7=34.5575191894877x_{7} = 34.5575191894877
x8=86.3937979737193x_{8} = -86.3937979737193
x9=45.553093477052x_{9} = -45.553093477052
x10=18.8495559215388x_{10} = -18.8495559215388
x11=20.4203522483337x_{11} = -20.4203522483337
x12=0x_{12} = 0
x13=64.4026493985908x_{13} = -64.4026493985908
x14=43.9822971502571x_{14} = 43.9822971502571
x15=43.9822971502571x_{15} = -43.9822971502571
x16=48.6946861306418x_{16} = 48.6946861306418
x17=58.1194640914112x_{17} = -58.1194640914112
x18=84.8230016469244x_{18} = 84.8230016469244
x19=39.2699081698724x_{19} = 39.2699081698724
x20=23.5619449019235x_{20} = 23.5619449019235
x21=80.1106126665397x_{21} = -80.1106126665397
x22=65.9734457253857x_{22} = -65.9734457253857
x23=69.1150383789755x_{23} = -69.1150383789755
x24=86.3937979737193x_{24} = 86.3937979737193
x25=45.553093477052x_{25} = 45.553093477052
x26=56.5486677646163x_{26} = 56.5486677646163
x27=51.8362787842316x_{27} = 51.8362787842316
x28=40.8407044966673x_{28} = 40.8407044966673
x29=87.9645943005142x_{29} = -87.9645943005142
x30=18.8495559215388x_{30} = 18.8495559215388
x31=62.8318530717959x_{31} = 62.8318530717959
x32=14.1371669411541x_{32} = -14.1371669411541
x33=53.4070751110265x_{33} = 53.4070751110265
x34=20.4203522483337x_{34} = 20.4203522483337
x35=468.097305384879x_{35} = 468.097305384879
x36=87.9645943005142x_{36} = 87.9645943005142
x37=59.6902604182061x_{37} = 59.6902604182061
x38=73.8274273593601x_{38} = -73.8274273593601
x39=31.4159265358979x_{39} = 31.4159265358979
x40=81.6814089933346x_{40} = -81.6814089933346
x41=72.2566310325652x_{41} = 72.2566310325652
x42=9.42477796076938x_{42} = -9.42477796076938
x43=29.845130209103x_{43} = -29.845130209103
x44=72.2566310325652x_{44} = -72.2566310325652
x45=81.6814089933346x_{45} = 81.6814089933346
x46=31.4159265358979x_{46} = -31.4159265358979
x47=89.5353906273091x_{47} = -89.5353906273091
x48=64.4026493985908x_{48} = 64.4026493985908
x49=94.2477796076938x_{49} = -94.2477796076938
x50=102.101761241668x_{50} = -102.101761241668
x51=50.2654824574367x_{51} = -50.2654824574367
x52=28.2743338823081x_{52} = 28.2743338823081
x53=29.845130209103x_{53} = 29.845130209103
x54=51.8362787842316x_{54} = -51.8362787842316
x55=92.6769832808989x_{55} = 92.6769832808989
x56=67.5442420521806x_{56} = -67.5442420521806
x57=100.530964914873x_{57} = 100.530964914873
x58=3.14159265358979x_{58} = -3.14159265358979
x59=53.4070751110265x_{59} = -53.4070751110265
x60=94.2477796076938x_{60} = 94.2477796076938
x61=21.9911485751286x_{61} = 21.9911485751286
x62=36.1283155162826x_{62} = -36.1283155162826
x63=15.707963267949x_{63} = -15.707963267949
x64=7.85398163397448x_{64} = -7.85398163397448
x65=65.9734457253857x_{65} = 65.9734457253857
x66=14.1371669411541x_{66} = 14.1371669411541
x67=6.28318530717959x_{67} = -6.28318530717959
x68=89.5353906273091x_{68} = 89.5353906273091
x69=80.1106126665397x_{69} = 80.1106126665397
x70=78.5398163397448x_{70} = 78.5398163397448
x71=15.707963267949x_{71} = 15.707963267949
x72=37.6991118430775x_{72} = 37.6991118430775
x73=42.4115008234622x_{73} = 42.4115008234622
x74=97.3893722612836x_{74} = -97.3893722612836
x75=70.6858347057703x_{75} = 70.6858347057703
x76=25.1327412287183x_{76} = -25.1327412287183
x77=36.1283155162826x_{77} = 36.1283155162826
x78=1.5707963267949x_{78} = -1.5707963267949
x79=95.8185759344887x_{79} = -95.8185759344887
x80=6.28318530717959x_{80} = 6.28318530717959
x81=23.5619449019235x_{81} = -23.5619449019235
x82=28.2743338823081x_{82} = -28.2743338823081
x83=40.8407044966673x_{83} = -40.8407044966673
x84=91.106186954104x_{84} = -91.106186954104
x85=67.5442420521806x_{85} = 67.5442420521806
x86=12.5663706143592x_{86} = 12.5663706143592
x87=37.6991118430775x_{87} = -37.6991118430775
x88=73.8274273593601x_{88} = 73.8274273593601
x89=58.1194640914112x_{89} = 58.1194640914112
x90=61.261056745001x_{90} = -61.261056745001
x91=1.5707963267949x_{91} = 1.5707963267949
x92=42.4115008234622x_{92} = -42.4115008234622
x93=47.1238898038469x_{93} = -47.1238898038469
x94=146.084058391925x_{94} = -146.084058391925
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 (sin(x)*cos(x))/(sin(x) + cos(x)).
sin(0)cos(0)sin(0)+cos(0)\frac{\sin{\left(0 \right)} \cos{\left(0 \right)}}{\sin{\left(0 \right)} + \cos{\left(0 \right)}}
Resultado:
f(0)=0f{\left(0 \right)} = 0
Punto:
(0, 0)
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
(sin(x)cos(x))sin(x)cos(x)(sin(x)+cos(x))2+sin2(x)+cos2(x)sin(x)+cos(x)=0\frac{\left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) \sin{\left(x \right)} \cos{\left(x \right)}}{\left(\sin{\left(x \right)} + \cos{\left(x \right)}\right)^{2}} + \frac{- \sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}}{\sin{\left(x \right)} + \cos{\left(x \right)}} = 0
Resolvermos esta ecuación
Raíces de esta ecuación
x1=3π4x_{1} = - \frac{3 \pi}{4}
x2=π4x_{2} = \frac{\pi}{4}
Signos de extremos en los puntos:
           ___  
 -3*pi  -\/ 2   
(-----, -------)
   4       4    

       ___ 
 pi  \/ 2  
(--, -----)
 4     4   


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=3π4x_{1} = - \frac{3 \pi}{4}
Puntos máximos de la función:
x1=π4x_{1} = \frac{\pi}{4}
Decrece en los intervalos
[3π4,π4]\left[- \frac{3 \pi}{4}, \frac{\pi}{4}\right]
Crece en los intervalos
(,3π4][π4,)\left(-\infty, - \frac{3 \pi}{4}\right] \cup \left[\frac{\pi}{4}, \infty\right)
Asíntotas verticales
Hay:
x1=0.785398163397448x_{1} = -0.785398163397448
Asíntotas horizontales
Hallemos las asíntotas horizontales mediante los límites de esta función con x->+oo y x->-oo
True

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

Tomamos como el límite
es decir,
ecuación de la asíntota horizontal a la derecha:
y=limx(sin(x)cos(x)sin(x)+cos(x))y = \lim_{x \to \infty}\left(\frac{\sin{\left(x \right)} \cos{\left(x \right)}}{\sin{\left(x \right)} + \cos{\left(x \right)}}\right)
Asíntotas inclinadas
Se puede hallar la asíntota inclinada calculando el límite de la función (sin(x)*cos(x))/(sin(x) + cos(x)), 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(sin(x)cos(x)x(sin(x)+cos(x)))y = x \lim_{x \to -\infty}\left(\frac{\sin{\left(x \right)} \cos{\left(x \right)}}{x \left(\sin{\left(x \right)} + \cos{\left(x \right)}\right)}\right)
True

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