Sr Examen

�(�)=cos(lnx)y la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
x*x = cos(log(x))*y
xx=ycos(log(x))x x = y \cos{\left(\log{\left(x \right)} \right)}
Solución detallada
Tenemos la ecuación
xx=ycos(log(x))x x = y \cos{\left(\log{\left(x \right)} \right)}
cambiamos
x2ycos(log(x))1=0x^{2} - y \cos{\left(\log{\left(x \right)} \right)} - 1 = 0
xxycos(log(x))1=0x x - y \cos{\left(\log{\left(x \right)} \right)} - 1 = 0
Sustituimos
w=cos(log(x))w = \cos{\left(\log{\left(x \right)} \right)}
Transportamos los términos libres (sin w)
del miembro izquierdo al derecho, obtenemos:
wy+x2=1- w y + x^{2} = 1
Dividamos ambos miembros de la ecuación en (x^2 - w*y)/w
w = 1 / ((x^2 - w*y)/w)

Obtenemos la respuesta: w = (-1 + x^2)/y
hacemos cambio inverso
cos(log(x))=w\cos{\left(\log{\left(x \right)} \right)} = w
sustituimos w:
Resolución de la ecuación paramétrica
Se da la ecuación con parámetro:
x2=ycos(log(x))x^{2} = y \cos{\left(\log{\left(x \right)} \right)}
Коэффициент при y равен
cos(log(x))- \cos{\left(\log{\left(x \right)} \right)}
entonces son posibles los casos para x :
x<eπ2x < e^{\frac{\pi}{2}}
x=eπ2x = e^{\frac{\pi}{2}}
x>eπ2x<e3π2x > e^{\frac{\pi}{2}} \wedge x < e^{\frac{3 \pi}{2}}
x=e3π2x = e^{\frac{3 \pi}{2}}
Consideremos todos los casos con detalles:
Con
x<eπ2x < e^{\frac{\pi}{2}}
la ecuación será
ycos(log(1+eπ2))+(1+eπ2)2=0- y \cos{\left(\log{\left(-1 + e^{\frac{\pi}{2}} \right)} \right)} + \left(-1 + e^{\frac{\pi}{2}}\right)^{2} = 0
su solución
y=(1eπ2)2cos(log(1+eπ2))y = \frac{\left(1 - e^{\frac{\pi}{2}}\right)^{2}}{\cos{\left(\log{\left(-1 + e^{\frac{\pi}{2}} \right)} \right)}}
Con
x=eπ2x = e^{\frac{\pi}{2}}
la ecuación será
eπ=0e^{\pi} = 0
su solución
no hay soluciones
Con
x>eπ2x<e3π2x > e^{\frac{\pi}{2}} \wedge x < e^{\frac{3 \pi}{2}}
la ecuación será
ycos(log(eπ22+e3π22))+(eπ22+e3π22)2=0- y \cos{\left(\log{\left(\frac{e^{\frac{\pi}{2}}}{2} + \frac{e^{\frac{3 \pi}{2}}}{2} \right)} \right)} + \left(\frac{e^{\frac{\pi}{2}}}{2} + \frac{e^{\frac{3 \pi}{2}}}{2}\right)^{2} = 0
su solución
y=(1+eπ)2eπ4sin(log(21+eπ))y = \frac{\left(1 + e^{\pi}\right)^{2} e^{\pi}}{4 \sin{\left(\log{\left(\frac{2}{1 + e^{\pi}} \right)} \right)}}
Con
x=e3π2x = e^{\frac{3 \pi}{2}}
la ecuación será
e3π=0e^{3 \pi} = 0
su solución
no hay soluciones
Gráfica
Respuesta rápida [src]
         /      2    \     /      2    \
         |     x     |     |     x     |
y1 = I*im|-----------| + re|-----------|
         \cos(log(x))/     \cos(log(x))/
y1=re(x2cos(log(x)))+iim(x2cos(log(x)))y_{1} = \operatorname{re}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)} + i \operatorname{im}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)}
y1 = re(x^2/cos(log(x))) + i*im(x^2/cos(log(x)))
Suma y producto de raíces [src]
suma
    /      2    \     /      2    \
    |     x     |     |     x     |
I*im|-----------| + re|-----------|
    \cos(log(x))/     \cos(log(x))/
re(x2cos(log(x)))+iim(x2cos(log(x)))\operatorname{re}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)} + i \operatorname{im}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)}
=
    /      2    \     /      2    \
    |     x     |     |     x     |
I*im|-----------| + re|-----------|
    \cos(log(x))/     \cos(log(x))/
re(x2cos(log(x)))+iim(x2cos(log(x)))\operatorname{re}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)} + i \operatorname{im}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)}
producto
    /      2    \     /      2    \
    |     x     |     |     x     |
I*im|-----------| + re|-----------|
    \cos(log(x))/     \cos(log(x))/
re(x2cos(log(x)))+iim(x2cos(log(x)))\operatorname{re}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)} + i \operatorname{im}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)}
=
    /      2    \     /      2    \
    |     x     |     |     x     |
I*im|-----------| + re|-----------|
    \cos(log(x))/     \cos(log(x))/
re(x2cos(log(x)))+iim(x2cos(log(x)))\operatorname{re}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)} + i \operatorname{im}{\left(\frac{x^{2}}{\cos{\left(\log{\left(x \right)} \right)}}\right)}
i*im(x^2/cos(log(x))) + re(x^2/cos(log(x)))