2018 E.A.P. DE INGENIERΓA CIVIL JORGE LUIS ORTEGA VARGAS 1) (π + ππ )π π + (π + ππ )π π = π ο (1 + π¦ 2 )ππ₯ = β(1 + π₯ 2
Views 108 Downloads 0 File size 1MB
2018
E.A.P. DE INGENIERΓA CIVIL
JORGE LUIS ORTEGA VARGAS
1) (π + ππ )π
π + (π + ππ )π
π = π ο (1 + π¦ 2 )ππ₯ = β(1 + π₯ 2 )ππ¦
ο ο
ππ₯
ππ¦
(1+π₯ 2 ) ππ₯
= β (1+π¦2) ππ¦
(1+π₯ 2 )
+ (1+π¦2) = 0 tan(π + π) =
ο
ππ₯
ππ¦
β« (1+π₯ 2 ) + β« (1+π¦2 ) = 0
tan(π) + tan(π) 1 β tan(π) β tan(π)
ο π‘ππβ1 (π₯) + π‘ππβ1 (π¦) = π‘ππβ1 (π) π₯+π¦
ο
π‘ππβ1 ( ) = π‘ππβ1 (π) 1βπ₯π¦
ο
(1βπ₯π¦) = π
π₯+π¦
ο π₯ + π¦ = π(1 β π₯π¦) β¦β¦RESPUESTA
2) (π + ππ )π
π + πππ
π = π ο (1 + π¦ 2 )ππ₯ = βπ₯π¦ππ¦
ο
ππ₯ π₯
ο β«
=β
ππ₯ π₯
π¦ππ¦ 1+π¦ 2
= ββ«
ο ln(π₯) = β
π¦ππ¦ 1+π¦ 2
ππ|1+π¦ 2 | 2
+ ln(π)
1
ο ln(π₯) = β ππ|1 + π¦ 2 | + ln(π) 2
1
ο ln(π₯) + ππ|1 + π¦ 2 | = ln(π)
1 1 ln(π) = ππ(π)2 2
2
ln(π) + ln(π) = ln(π β π)
ο ln(π₯) + ππβ1 + π¦ 2 = ln(π) ο πππ₯ 2 (1 + π¦ 2 ) = ln(π) ο π₯ 2 (1 + π¦ 2 ) = π
β¦..RESPUESTA
EJERCICIO 3 (ππ + πππ )πΒ΄ + ππ β ππ π = π SoluciΓ³n: π¦ 2 (1 + π₯)π¦Β΄ + π₯ 2 (1 β π¦) = 0 π¦ 2 (1 + π₯)
ππ¦ = βπ₯ 2 (1 β π¦) ππ₯
π¦ 2 (1 + π₯)ππ¦ = βπ₯ 2 (1 β π¦)ππ₯ π¦ 2 (1 + π₯)ππ¦ = π₯ 2 (π¦ β 1)ππ₯ π¦2 π₯2 ππ¦ = ππ₯ (π¦ β 1) (1 + π₯) β«
π¦2 π₯2 ππ¦ = β« ππ₯ (1 + π₯) (π¦ β 1)
π¦2 β π¦ π¦ β 1 1 π₯2 + π₯ π₯ + 1 1 β«( + + β + ) ππ¦ = β« ( ) ππ₯ (1 + π₯) π₯ + 1 1 + π₯ π¦β1 π¦β1 π¦β1 β« (π¦ + 1 +
1 1 ) ππ¦ = β« (π₯ β 1 + ) ππ₯ π¦β1 1+π₯
π¦2 π₯2 + π¦ + ln|π¦ β 1| = β π₯ + ln|1 + π₯| 2 2 Respuesta: (x + y)(x β y β 2) + 2ln |
1+π₯ |=πΆ 1βπ¦
EJERCICIO 4 (π + ππ )π
π = ππ
π SoluciΓ³n: (1 + π¦ 2 )ππ₯ = π₯ππ¦ 1 1 ππ₯ = ππ¦ π₯ 1 + π¦2 1 1 β« ππ₯ = β« ππ¦ π₯ 1 + π¦2 πππ₯ = arctan(π¦) tan[arctan(π¦)] = tan. lnx Respuesta: π¦ = π‘ππ. πππ₯πΆ
π. βπΏβπ + ππ + ππβ² βπ + πΏπ = π βΉ πβ1 + π 2 + π βΉ π
ππ¦ β1 + π 2 = 0 ππ₯
ππ¦ β1 + π 2 = β πβ1 + π 2 ππ₯
βΉ πππ¦β1 + π 2 = β πβ1 + π 2 ππ₯ βΉ πππ¦β1 + π 2 = β πβ1 + π 2 ππ₯ βΉ βΉ βΉ
π β1 +
π2
π β1 + π 2 π β1 + π 2
βΉ β«
ππ¦ = β ππ¦ = β ππ₯ +
π β1 + π 2
π»π΄πΆπΌπΈππ·π:
π β1 + π 2 π β1 + π 2 π
β1 + π 2
ππ₯ + β«
ππ₯ ππ₯
ππ¦ = 0
π β1 + π 2
ππ¦ = β«0
π΄= β« π΅= β«
π β1 + π 2 π
β1 + π 2
ππ₯
ππ¦
Resolviendo A β«
π β1 + π 2
ππ₯ ; π’ = 1 + π 2
ππ’ = 2π₯ππ₯ β ππ₯ =
1 ππ’ 2π₯
Reemplazando: β«
π
1 ππ’) βπ’ 2π₯ (
βΉβ«
1 2βπ’
ππ’
βΉ
1 ππ’ β« 2 βπ’
βΉ
1 1 β« π’β2 ππ’ 2 1
1 π’2 βΉ ( ) 2 1 2
1
1 π’2 βΉ (2 β ) 2 1 1
βΉ π’2
Remplazando el valor de π’ = 1 + π 2 1
β΄ π΄ = (1 + π 2 )2 = β1 + π 2
Resolviendo B β«
π β1 + π 2
ππ¦ ; π£ = 1 + π 2
Reemplazando: β«
π
1 ππ£) βπ£ 2π (
ππ’ = 2πππ¦ β ππ¦ =
1 ππ’ 2π
βΉβ«
1 2βπ£
ππ£
βΉ
1 ππ£ β« 2 βπ£
βΉ
1 1 β« π£ β2 ππ£ 2 1
1 π£2 βΉ ( ) 2 1 2
1
1 π£2 βΉ (2 β ) 2 1 1
βΉ π£2
Remplazando el valor de π£ = 1 + π 2 1
β΄ π΅ = (1 + π 2 )2 = β1 + π 2
JUNTANDO A Y B: β1 + π 2 + β1 + π 2 = β« 0
RPTA: β΄ βπ + π π + βπ + π π = π
π. β πΏβπ β ππ π
π + πβπ β πΏπ π
π = π βΉ πβ1 β π 2 ππ₯ = πβ1 β π 2 ππ¦ = 0 βΉ πβ1 β π 2 ππ₯ = β (πβ1 β π 2 ππ¦) βΉ βΉ
π β1 β π 2 π β1 β π 2
βΉ β«
ππ₯ = β ππ₯ +
π β1 β π 2
π»π΄πΆπΌπΈππ·π:
π β1 β π 2 π
β1 β π 2
ππ₯ + β«
ππ¦
ππ¦ = 0 π
β1 β π 2
ππ¦ = β« 0
, π(π) = π
π΄= β« π΅= β«
π β1 β π 2 π
β1 β π 2
ππ₯
ππ¦
Resolviendo A β«
π β1 β π 2
ππ₯ ; π’ = 1 β π 2
ππ’ = β2πππ₯ β ππ₯ = β
1 ππ’ 2π
Reemplazando: β«
π βπ’
(β
βΉ β«β
1 ππ’) 2π 1
2 βπ’
ππ’
1 ππ’ βΉβ β« 2 βπ’ 1 1 βΉ β β« π’β2 ππ’ 2 1
1 π’2 βΉβ ( ) 2 1 2
1
1 π’2 βΉ β (2 β ) 2 1 1
βΉ βπ’2
Remplazando el valor de π’ = 1 β π 2 1
β΄ π΄ = β(1 β π 2 )2 = ββ1 β π 2
Resolviendo B β«
π β1 β π 2
ππ¦ ; π£ = 1 β π 2
Reemplazando: β«
π βπ’
(β
1 ππ£) 2π¦
ππ£ = β2πππ¦ β ππ¦ = β
1 ππ£ 2π
βΉ β«β
1 2 βπ£
ππ£
1 ππ£ βΉβ β« 2 βπ£ 1 1 βΉ β β« π£ β2 ππ£ 2 1
1 π£2 βΉβ ( ) 2 1 2
1
1 π£2 βΉ β (2 β ) 2 1 1
βΉ βπ£ 2
Remplazando el valor de π£ = 1 β π 2 1
β΄ π΄ = β(1 β π 2 )2 = ββ1 β π 2 JUNTANDO A Y B: β1 β π 2 + β1 β π 2 = β« 0 β1 β π 2 + β1 β π 2 = πΆ Sustituyendo la condiciΓ³n inicial π = 1 cuando π = 0 β1 β 02 + β1 β 12 = πΆ βΉ1=πΆ
RPTA: β΄ βπ β πΏπ + βπ β ππ = π , π = π 7) πβπ (π β πβ²) = π β (1 β π¦β²) =
β
1 π βπ¦
ππ¦ 1 = (1 β βπ¦ ) ππ₯ π
β 1β
1 π βπ¦
= π¦β²
β ππ¦ = (1 β
1 π βπ¦
)
π βπ¦ β 1 β ( βπ¦ ) ππ₯ = ππ¦ π β ππ₯ β
π βπ¦ ππ¦ = 0 (π βπ¦ β 1)
π βπ¦ ππ’ βπ₯+β« =πΆ π’ π βπ¦
β
β
β« ππ₯ β β«
π₯+β«
π βπ¦ = β«0 (π βπ¦ β 1)
ππ’ +πΆ =0 π’
β π₯ + ln β£ π’ β£= πΆ β π₯ + ln β£ π βπ¦ β 1 β£= πΆ β ln β£ π βπ¦ β 1 β£= πΆ β π₯ β π βπ¦ β 1 = π (πβπ₯) β π βπ¦ β 1 = π π π βπ₯
β
1 π βπ¦
β1=
β
π βπ¦ β 1 = π βπ₯ π
π ππ₯
1 1 +1= π¦ βπ₯ π π
π = π βπ¦ β 1 ππ₯
β
πΆ = π π₯ (π βπ¦ β 1)
β
π π₯ = πΆ(π βπ¦ β 1)β1
8) π π₯π§ π π
π + ππ
π = π
β
ππ₯ ππ¦ + =0 π₯ π¦ ln(π¦)
π
πππ β (π(π) = π)
π’ = ln(π¦) ππ’ =
ββ«
ππ₯ ππ¦ +β« = β«0 + π₯ π¦ ln(π¦)
ππ¦ π¦
β ln β£ π₯ β£ + β«
ππ¦ =πΆ π¦ ln(π¦)
β ln β£ π₯ β£ + β«
π¦ππ’ =πΆ π¦(π’)
β ln β£ π₯ β£ + β«
ππ’ =πΆ π’
β ln β£ π₯ β£ + ln β£ π’ β£= πΆ β ln β£ (π₯) (π’) β£= πΆ β ln β£ π₯ ln(π¦) β£= πΆ β π₯ ln(π¦) = π π β π₯ ln(π¦) = πΆ
β
π₯ ln(π¦) = π π
πππππ: π¦0 = 1 πππ ππ π‘πππ‘π β π₯ = 1 ;
π¦=1
Ejercicio.9 πβ² = ππ+π ππ¦ = ππ¦ . ππ₯ ππ₯ ππ¦ = π π₯ . ππ₯ ππ¦ β«
ππ¦ = β« π π₯ . ππ₯ ππ¦
β« πβπ¦ . ππ¦ = β« π π₯ . ππ₯ β β«(β). πβπ¦ . ππ¦ = β« π π₯ . ππ₯ π βπ¦ ππ₯ β = +π ln π ln π πβπ¦ ππ₯ = β βπ ln π ln π
πβπ¦ = βπ π₯ β ln π . π βπ¦ = log π (βπ π₯ β ln π . π) π¦ = β log π (π β π π₯ ) π¦ = log π (
1 ) π β ππ₯
Ejercicio.10
βππ(π + ππ )π
π + ππ (π + ππ )π
π = π π π¦ (1 + π₯ 2 )ππ¦ = 2π₯(1 + π π¦ )ππ₯ β«
ππ¦ 2π₯ . ππ¦ = β« . ππ₯ π¦ 1+π 1 + π₯2
1
2
Integrando 1
Integrando 2
ππ¦ β« . ππ¦ 1 + ππ¦
β«
1 + ππ¦ = π£
1 + π₯2 = π£
π π¦ . ππ¦ = ππ£
2π₯. ππ₯ = ππ£
ππ¦ = β«
ππ£ ππ¦
2π₯ . ππ₯ 1 + π₯2
ππ₯ =
π π¦ ππ£ . π£ ππ¦
β«
ππ£ 2π₯
2π₯ ππ£ . π£ 2π₯
β« π£ β1 . ππ£
β« π£ β1 . ππ£
ln(π£) + π1
ln(π£) + π2
ln(1 + π π¦ ) + π1
ln(1 + π₯ 2 ) + π2
Sustituyendo ln(1 + π π¦ ) = ln(1 + π₯ 2 ) + π 1 + π π¦ = π ln(1+π₯ π π¦ = π ln(1+π₯
2 )+π
π¦ = ln(π ln(1+π₯
2 )+π
β1
2 )+π
11.(π β ππβ² )π = ππ + ππ
β(π¦ β π₯π¦ β² )2 = βπ₯ 2 + π¦ 2 Β±(π¦ β π₯π¦ β² ) = βπ₯ 2 + π¦ 2 a). cuando toma positivo. (π¦ β π₯π¦ β² ) = βπ₯ 2 + π¦ 2 π¦ β βπ₯ 2 + π¦ 2 = π¦ β² π₯ 1 1 (π¦ β βπ₯ 2 + π¦ 2 ) = (π¦ β² π₯) π₯ π₯ π¦ π¦ 2 β β1 + ( ) π₯ π₯
=
ππ¦ ππ₯
Hacemos un cambio de variable. π¦ =π£ π₯ ππ¦ ππ£ = π₯+π£ ππ₯ ππ₯
Reemplazando: π£ β β1 + π£ 2 = ββ1 + π£ 2 = β
ππ£ π₯+π£ ππ₯
ππ£ π₯ ππ₯
ππ₯ ππ£ = π₯ β1 + π£ 2
ββ«
ππ₯ ππ£ =β« π₯ β1 + π£ 2
β ln π₯ = β ln |β1 + π£ 2 β π£| + ln πΆ ln π₯πΆ = ln |β1 + π£ 2 β π£| π₯πΆ = β1 + π£ 2 β π£ 2
(π₯πΆ + π£)2 = (β1 + π£ 2 )
π₯ 2 πΆ 2 + 2π£π₯πΆ + π£ 2 = 1 + π£ 2 π₯ 2 πΆ 2 + 2πΆπ¦ = 1
b). cuando es negativo. β(π¦ β π₯π¦ β² ) = βπ₯ 2 + π¦ 2 π¦ 2 π¦ π¦ β² = β1 + ( ) + π₯ π₯ ππ£ π₯ + π£ = β1 + π£ 2 + π£ ππ₯ ππ£ π₯ = β1 + π£ 2 ππ₯ ππ£ β1 + π£ 2
=
ππ₯ π₯
β ln |β1 + π£ 2 β π£| = ln π₯ β ln πΆ πΆ β ln |β1 + π£ 2 β π£| = β ln ( ) π₯ β1 + π£ 2 β π£ = β1 +
π£2
2
1 + π£2 = 1=
πΆ π₯
2 πΆ = ( + π£) π₯
πΆ2 πΆ + 2π£ + π£2 π₯2 π₯
πΆ 2 2π¦πΆ + 2 π₯2 π₯
π₯ 2 β πΆ 2 = 2π¦πΆ
12)(π + ππ )(πππ π
π β ππ π
π) β (π + π)π
π = π (1 + π¦ 2 )π 2π₯ ππ₯ β (1 + π¦ 2 )π π¦ ππ¦ β (1 + π¦)ππ¦ = 0 (1 + π¦ 2 )π 2π₯ ππ₯ = ((1 + π¦ 2 )π π¦ + 1 + π¦)ππ¦ π 2π₯ ππ₯ = (π π¦ +
1 π¦ + ) ππ¦ 1 + π¦2 1 + π¦2
β« π 2π₯ ππ₯ = β« (π π¦ +
1 π¦ + )ππ¦ 1 + π¦2 1 + π¦2
π 2π₯ ln|1 + π¦ 2 | π¦ =π + + tanβ1 π¦ + πΆ 2 2 π 2π₯ ln|1 + π¦ 2 | π¦ βπ β β tanβ1 π¦ = πΆ β¦ β¦ . πππ ππ’ππ π‘π 2 2 13) (π₯π¦ 2 β π¦ 2 + π₯ β 1)ππ₯ + (π₯ 2 π¦ β 2π₯π¦ + π₯ 2 + 2π¦ β 2π₯ + 2)ππ¦ = 0 [π¦ 2 (π₯ β 1) + (π₯ β 1)]ππ₯ + [π₯ 2 (π¦ + 1) β 2π₯(π¦ + 1) + 2(π¦ + 1)]ππ¦ = 0 (π₯ β 1)(π¦ 2 + 1)ππ₯ + (π¦ + 1)[π₯ 2 β 2π₯ + 2]ππ¦ = 0 (π₯β1)ππ₯ (π₯ 2 β2π₯+2)
+
(π¦+1)ππ¦ (π¦ 2 +1)
=0
Integrando la ecuaciΓ³n diferencial (π₯β1)ππ₯
β« (π₯ 2 β2π₯+2) + β« (π₯β1)π
(π¦+1)ππ¦ (π¦ 2 +1)
= β«0
π¦ππ¦
ππ¦
β« (π₯β1)2 +1 + β« (π¦ 2 +1) + β« (π¦ 2 +1) = πΆ π¦ 2 + 1 = π‘ β 2π¦ππ¦ = ππ‘
Donde: π = π₯ β 1 β ππ = ππ₯; πππ
π¦ππ‘
ππ¦
β« π2 +1 + β« 2π‘π¦ + β« (π¦ 2 +1) = πΆ 1
1
ππ|π2 + 1| + 2 ππ|π¦ 2 + 1| + arctan(π¦) = πΆ 2 1 2
1
ππ|(π₯ β 1)2 + 1| + 2 ππ|π¦ 2 + 1| + arctan(π¦) = πΆ
ππ|((π₯ β 1)2 + 1)(π¦ 2 + 1)| = 2πΆ β 2arctan(π¦) (π₯ 2 β 2π₯ + 2)(π¦ 2 + 1) = π 2πΆβ2arctan(π¦) (π₯ 2 β 2π₯ + 2)(π¦ 2 + 1) = π 2πΆ π β2 arctan(π¦) (π₯ 2 β 2π₯ + 2)(π¦ 2 + 1)π 2 arctan(π¦) = πΆ
14) π¦ β² = π ππ(π₯ β π¦) ππ¦ ππ₯
= π ππ(π₯ β π¦)
Haciendo cambio de variables donde: π₯ β π¦ = π§; ππ§
ππ₯ β ππ¦ = ππ§ ππ§
ππ¦
ππ§
β ππ₯ = 1 β ππ₯ ππ§
1 β ππ₯ = π ππ(π§) β ππ₯ = 1 β π ππ(π§) β ππ₯ β (1βπ ππ(π§)) =0
ππ§
ππ§
ππ₯ β (1βπ ππ(π§)) = 0
β β« ππ₯ β β« (π ππ(π§)+1) = β« 0
(1+π ππ(π§))ππ§
π₯ β β« (1βπ ππ(π§))(1+π ππ(π§)) = πΆ π₯ββ«
(1+π ππ(π§))ππ§
=πΆ
(1βπ ππ(π§)2 ) ππ§
β β« πππ (π§)2 β β«
βπ₯ββ«
π ππ(π§)ππ§
(1+π ππ(π§))ππ§ πππ (π§)2
=πΆ
+ π₯ = πΆ β β β« π ππ(π§)2 ππ§ β β« π ππ(π§)πππ (π§)β2 ππ§ + π₯ = 0
πππ (π§)2
x β tan(π§) + πππ (π§)β1 = πΆ Reemplazando el valor de βzβ 1
π₯ β tan(π₯ + π¦) β cos(π₯+π¦) = πΆ π ππ(π₯+π¦)
1
π₯ β cos(π₯+π¦) β cos(π₯+π¦) = πΆ π₯=πΆβ
π ππ(π₯+π¦)β1 cos(π₯+π¦)
Remplazando por su equivalencia en radianes nos queda: π₯ = πππ‘π (
π¦βπ₯ 2
π
+ 4) = πΆ
EJERCICIO 15: π¦Β΄ = ππ₯ + ππ¦ + π
ο¨ο¨
DΓ³nde: (a, b y c) son constantes
RESOLUCION: π¦Β΄ = ππ₯ + ππ¦ + π ππ¦ = ππ₯ + ππ¦ + π ππ₯ Haremos un cambio de variable: ππ₯ + ππ¦ + π = π§ ====> πππ₯ + πππ¦ + 0 = ππ§ ====> πππ¦ = ππ§ β πππ₯ ππ¦
Dividimos entre dx para tener (ππ₯ ) ππ¦ ππ§ π β ππ₯ ππ¦ ππ§ π = β =======> = β ππ₯ π β ππ₯ π β ππ₯ ππ₯ π β ππ₯ π Reemplazamos en la ecuaciΓ³n: ππ¦ ππ¦ ππ§ π ππ§ π = (ππ₯ + ππ¦ + π) ====> = π§ =====> β = π§ ===> = π§+ ππ₯ ππ₯ π β ππ₯ π π β ππ₯ π π ππ§ ππ§ = (π§ + ) (π β ππ₯) ====> π β πππ₯ = 0 π (π§ + ) π
ππ§
π β β« πππ₯ = β« 0 ======> ππ + |π§ | β ππ₯ = π π π (π§ + ) π π ln |π§ + | = π + ππ₯ π β«
Por propiedad de logaritmos: π ln |π§ + | = π + ππ₯ π π π§ + = π π+ππ₯ π ππ₯ + ππ¦ + π = π§
Reemplazando el valor de Z: π§+
π π = π π+ππ₯ ===> ππ₯ + ππ₯ + π + = π π+ππ₯ π π
π + π(ππ₯ + ππ₯ + π) = π π+ππ₯ RESPUESTA: π + π(ππ₯ + ππ₯ + π) = π π+ππ₯ ===> π + π(ππ₯ + ππ₯ + π) = π β π ππ₯ π + π(ππ₯ + ππ₯ + π) = π β π ππ₯
EJERCICIO 16: (π₯ + π¦)2 ππ¦Β΄ = π2 RESOLUCION: ππ¦
(π₯ + π¦)2 ππ¦Β΄ = π2 ===> (π₯ + π¦)2 = π2 ππ₯ βππππππ π’π ππππππ ππ π£πππππππ πππππ: π₯ + π¦ = π§ π₯ + π¦ = π§ ο¨ ππ₯ + ππ¦ = ππ§ πππ£ππππππ πππ‘ππ (ππ₯) πππππππ π πππππππ ππ₯ ππ¦ ππ§ ππ¦ ππ§ + = ==> = β1 ππ₯ ππ₯ ππ₯ ππ₯ ππ₯ Reemplazamos en la ecuaciΓ³n original: (π₯ + π¦)2
ππ¦ ππ¦ ππ§ = π2 =====> (π§)2 = π2 ====> (π§)2 ( β 1) = π2 ππ₯ ππ₯ ππ₯
(π§)2 ππ§ β (π§)2 ππ₯ = π2 ππ₯ ====> (π§)2 ππ§ = (π2 + (π§)2 )ππ₯ (π§)2 ππ§ (π§)2 ππ§ β ππ₯ = 0 β¦ β¦ β¦ β¦ πππ ππππ π πππ‘πππππ ==> β« β β« ππ₯ = β« 0 π2 + (π§)2 π2 + (π§)2
β«
[(π§)2 + π2 β π2 ]ππ§ β β« ππ₯ = β« 0 π2 + (π§)2
β«
[(π§)2 + π2 ]ππ§ π2 ππ§ β β« β β« ππ₯ = π π2 + (π§)2 π2 + (π§)2
β« ππ§ β π2 β β«
π2
ππ§ 1 π§ β π₯ = π ====> π§ β π2 ( ) arctan ( ) β π₯ = π 2 + (π§) π π π₯+π¦ =π§
Reemplazamos la variable Z:
π₯+π¦ π₯+π¦ π§ β π β arctan ( ) β π₯ = π =====> π₯ + π¦ β π β arctan ( )βπ₯ = π π π π₯+π¦ π₯+π¦ π¦βπ π β arctan ( ) = π¦ β π ====> arctan ( )= π π π
π¦βπ π₯+π¦ π¦ π₯+π¦ tan ( )= ====> tan ( β π) = π π π π RESPUESTA: π¦ π β tan ( β π) = π₯ + π¦ π
(17) (π β π)ππ πβ² +
ππ
=π
ππππ
(1 β π¦)π π¦
ππ¦ π¦2 + =0 ππ₯ π₯πππ₯
Separando variables obtenemos (1 β π¦)π π¦ ππ¦ ππ₯ = 2 π¦ π₯πππ₯ π π¦ ππ¦ β π¦ππ¦ ππ₯ = 2 π¦ π₯πππ₯
Integrando
ππ¦ π¦ ππ₯ β« 2 ππ¦ β β« 2 ππ₯ = β« π¦ π¦ π₯πππ₯
De la integraciΓ³n obtenemos
ππ¦ π¦
= ln|πππ₯| + π
π
(π + ππ )π
π = (π β βπ β ππ )(π + ππ )π π
π
(18)
Separando variables obtenemos ππ₯ 3
=
(1 + π₯ 2 )2
(π¦ β β(1 + π¦ 2 ) ππ¦ (1 + π¦ 2 )
Integrando ππ₯ 3
(1 + π₯ 2 )2 ππ₯
β«
3
(1 + π₯ 2 )2
=
π¦ β(1 + π¦ 2 ) ππ¦ β ππ¦ (1 + π¦ 2 ) (1 + π¦ 2 )
=β«
π¦ β(1 + π¦ 2 ) ππ¦ β β« ππ¦ (1 + π¦ 2 ) (1 + π¦ 2 )
Integrando obtenemos
ππ
β1 + π¦ 2 |π¦ + β1 + π¦ 2 |
=
19) πππ (ππΒ΄ + π) = ππ π₯ 2 π¦ 2 π¦Β΄ + π₯π¦ 3 = π2 π₯2π¦2
ππ¦ + π₯π¦ 3 = π2 ππ₯
π₯2π¦2
ππ¦ = π2 β π₯π¦ 3 ππ₯
π₯ 2 π¦ 2 ππ¦ β (π2 β π₯π¦ 3 )ππ₯ = 0 (π2 β π₯π¦ 3 )ππ₯ β π₯ 2 π¦ 2 ππ¦ = 0 DERIVANDO RESPECTO A βXβ ο· ο· π(π₯) =
(π2 β π₯π¦ 3 )ππ₯ = β3π₯π¦ 2 β¦β¦β¦β¦ππ¦ βπ₯ 2 π¦ 2 ππ¦ = β2π₯π¦ 2 β¦β¦β¦β¦β¦β¦.ππ₯ ππ¦ β ππ₯ β3π₯π¦ 2 + 2π₯π¦ 2 βπ₯π¦ 2 1 = = = 2 2 2 2 π βπ₯ π¦ βπ₯ π¦ π₯
π₯ β1 + π₯ 2
+π
1
π(π₯) = π β«π₯ππ₯ = π πΏπ(π₯) π(π₯) = π₯ ο (π2 π₯ β π₯ 2 π¦ 3 )ππ₯ β π₯ 3 π¦ 2 ππ¦ = 0 ππ¦ =-3π₯ 2 π¦ 2
ππ¦ = ππ₯
ππ₯ =-3π₯ 2 π¦ 2 INTEGRANDO RESPECTO A βyβ ο·
β«(βπ₯ 3 π¦ 2 )ππ¦
β β« π₯ 3 π¦ 2 ππ¦ = β π₯ 3 β« π¦ππ¦ π(π₯, π¦) = β
π₯3π¦3 + π(π₯) 3
DERIVANDO RESPECTO A βXβ
β
πππ ππ + πΒ΄(π) = ππ (π) β ππ ππ π
πΒ΄(π₯) = π2 (π₯)β¦β¦..β¦β¦β¦β« πΒ΄(π₯) = β« π2 π₯ππ₯ ο° π(π₯) =
π2 π₯2 2 π₯ 3π¦3 π2 π₯ 2 + 3 2 π2 π₯ 2 =0 2
οΆ π(π₯, π¦) = β οΆ =β
π₯ 3π¦3 3
+
οΆ πππ ππ = πππ ππ
RPTA
ππ) (ππ ππ + π)π
π + πππ π
π = π ο° π§ = π₯π¦ π§ π¦= π₯ π₯ππ§ β π§ππ₯ ππ¦ = π₯2 SUSTITUYENDO: (π₯ 2 π¦ 2 + 1)ππ₯ + 2π₯ 2 ππ¦ = 0 (π§ 2 + 1)ππ₯ + 2π₯ 2 β
π₯ππ§ β π§ππ₯ =0 π₯2
(π§ 2 + 1)ππ₯ β 2π§ππ₯ + 2π₯ππ§ = 0 (π§ 2 β 2π§ + 1)ππ₯ + 2π₯ππ§ = 0
ππππππππππ π = ππ
(π§ 2 β 1)2 ππ₯ = β2π₯ππ§ ππ₯ ππ§ = 2 β2π₯ (π§ β 1)2
INREGRANDO: β«
ππ₯ ππ§ =β« 2 β2π₯ (π§ β 1)2
β1 ππ₯ ππ§ β« =β« 2 2 π₯ (π§ β 1)2 β1 1 πΏπ(π₯) = β +π 2 π§β1 π=
1 1 + πΏπ(π₯) 1βπ§ 2
π=
1 1 + πΏπ(π₯) 1 β π₯π¦ 2
π=
π πβππ
π
+ π³π(π) = π π
RPTA
21). (π₯ 2 π¦ 2 + 1)π¦ + (π₯π¦ β 1)2 π₯π¦Β΄ = 0 (π₯ 2 π¦ 2 + 1)π¦ + (π₯π¦ β 1)2 π₯π¦Β΄ = 0 (π₯ 2 π¦ 2 + 1)π¦ππ₯ + (π₯π¦ β 1)2 π₯ππ¦ = 0 β¦ β¦ β¦ β¦ β¦ . π½
π₯π¦ = π
πππ‘πππππ π¦ππ₯ + π₯ππ¦ = ππ
π₯ππ¦ = ππ β π¦ππ₯ ππ¦ =
ππ π¦ β ππ₯ β¦ β¦ β¦ β¦ β¦ . πΌ π₯ π₯ πΌ ππ π½
ππ π¦ (π2 + 1)π¦ππ₯ + (π β 1)2 π₯ ( β ππ₯) = 0 π₯ π₯ (π2 + 1)π¦ππ₯ + (π β 1)2 π₯
ππ π¦ β (π β 1)2 π₯ ππ₯ = 0 π₯ π₯
[(π2 + 1)π¦ β (π β 1)2 π¦]ππ₯ + (π β 1)2 ππ = 0 [(π2 + 1) β (π2 β 2π + 1)]π¦ππ₯ + (π β 1)2 ππ = 0
[π2 + 1 β π2 + 2π β 1]π¦ππ₯ + (π β 1)2 ππ = 0 π
2ππ¦ππ₯ + (π β 1)2 ππ = 0
β¦β¦β¦β¦β¦β¦β¦β¦β¦ π¦ = π₯
π 2π ππ₯ + (π β 1)2 ππ = 0 π₯ π2 2 ππ₯ + (π β 1)2 ππ = 0 π₯
β
2 (π2 β 2π + 1) ππ₯ + ππ = 0 π₯ π2
ππ₯ (π2 β 2π + 1) 2β« +β« ππ = β« 0 π₯ π2 2 ln|π₯| + β« (1 β
2 1 + ) ππ = πΆ π π2
1 1 2 ln|π₯| + β« ππ β 2 β« ππ + β« ( 2 ) ππ = πΆ π π 2 ln|π₯| + π β 2 ln|π| + πβ1 = πΆ
π+
β1 = 2 ln|π| β 2 ln|π₯| π
πβ
1 π = 2 ln | | π π₯
πβ
1 π₯π¦ = 2 ln | | π π₯
β
2 ln|π₯| + π β 2 ln|π| +
1
ln|π¦ 2 | = π β π πππππππ§ππππ π ππ π₯π¦ ππππππππ π ππ πππ ππ’ππ π‘π ln|π¦ 2 | =
1 β π₯π¦ π₯π¦
para eliminar (Ln)πππ‘ππππππππ (πΏπ) ππ "πβ e
ln |π¦ 2 |
=
1 βπ₯π¦ π₯π¦ π
ππππππππ π ππ πππ ππ’ππ π‘π
1
π¦ 2 = π π₯π¦
βπ₯π¦
β1 =πΆ π
22) (ππ ππ + π + π β π)π
π + (ππ ππ + π)π
π = π Haciendo cambio de variable donde: π₯π¦ = π§ ;
π₯ππ¦ + π¦ππ₯ = ππ§ β ππ¦ =
ππ§ π₯
β
π¦ππ₯ π₯
(π§ 2 π¦ + π¦ + π₯ β 2)ππ₯ + (π§ 2 π₯ + π₯)ππ¦ = 0 (π§ 2 π¦ + π¦ + π₯ β 2)ππ₯ + π₯(π§ 2 + 1) [
ππ§ π₯
β
π¦ππ₯ ] π₯
=0
(π§ 2 π¦ + π¦ + π₯ β 2)ππ₯+(π§ 2 + 1)ππ§ β π¦(π§ 2 + 1)ππ₯ = 0 [(π§ 2 π¦ + π¦ + π₯ β 2) β π¦(π§ 2 + 1)]ππ₯ + (π§ 2 + 1)ππ§ = 0 [π§ 2 π¦ + π¦ + π₯ β 2 β π¦π§ 2 β π¦] + ππ₯(π§ 2 + 1)ππ§ = 0 (π₯ β 2)ππ₯ + (π§ 2 + 1)ππ§ = 0 β β«(π₯ β 2)ππ₯ + β«(π§ 2 + 1)ππ§ = β« 0 β« π₯ππ₯ β 2 β« ππ₯ + β« π§ 2 ππ§ + β« ππ§ = πΆ π₯2 2
β 2π₯ +
π§3 3
+π§ =πΆ
β
π₯2 2
β 2π₯ +
(π₯π¦)3 3
+ π₯π¦ = πΆ
3π₯ 2 β 12π₯ + 2(π₯π¦)3 + 6π₯π¦ = πΆ
23) (ππ β πππ + πππ β ππ + πππ π)π
π + (πππ β πππ )π
π = π Buscando factor de integraciΓ³n πππ₯ + πππ¦ = 0 π = π₯ 6 β 2π₯ 5 + 2π₯ 4 β π¦ 3 + 4π₯ 2 π¦ π = π₯π¦ 2 β 4π₯ 3 Haciendo deriva parcial de (ππ¦ ; ππ₯ ) ππ¦ = β3π¦ 3 + 4π₯ 2 ππ¦ = π¦ 3 β 12π₯ 2 donde: π(π₯) = πΆ β¦β¦β¦β¦β¦β¦β¦β¦β¦.(1) o tambiΓ©n π(π¦) =
ππ₯ βππ¦ π
β¦β¦β¦β¦β¦β¦β¦β¦β¦β¦(2)
desarrollando en la ecuaciΓ³n π(π₯) π(π₯) =
β3π¦ 3 +4π₯ 2 β(π¦ 3 β12π₯ 2 ) π₯π¦ 2 β4π₯ 3
π(π₯) =
β4 π₯
=
β3π¦ 3 +4π₯ 2 βπ¦3 +12π₯ 2 π₯(π¦ 2 β4π₯ 2 )
=
β3π¦ 3 +4π₯ 2 βπ¦ 3 +12π₯ 2 π₯(π¦ 2 β4π₯ 2 )
Reemplazando en la siguiente fΓ³rmula π(π₯) = π β« π(π₯)ππ₯
=
β4(π¦ 2 β4π₯ 2 ) π₯(π¦ 2 β4π₯ 2 )
β4
π(π₯) = π β« π₯
ππ₯
ππ₯
= π β4 β« π₯ = π β4ln(π₯) = π ln(π₯
β4 )
π(π₯) = π₯ β4 multiplicar a ecuaciΓ³n diferencial por la funciΓ³n π(π₯) = π₯ β4 π₯ β4 (π₯ 6 β 2π₯ 5 + 2π₯ 4 β π¦ 3 + 4π₯ 2 π¦)ππ₯ + π₯ β4 (π₯π¦ 2 β 4π₯ 3 )ππ¦ = 0 (π₯ 2 β 2π₯ + 2 β π¦ 3 π₯ β4 + 4π₯ β2 π¦)ππ₯ + (π₯ β3 π¦ 2 β 4π₯ β1 )ππ¦ = 0 Comprobando si la ecuaciΓ³n diferencial es exacta π = π₯ 2 β 2π₯ + 2 β π¦ 3 π₯ β4 + 4π₯ β2 π¦ π = π₯ β3 π¦ 2 β 4π₯ β1 Haciendo deriva parcial de (ππ¦ ; ππ₯ ) ππ¦ = β3π₯ β4 π¦ 2 + 4π¦ β2 ππ₯ = β3π₯ β4 π¦ 2 + 4π¦ β2 Donde (ππ₯ = ππ¦ ) son iguales entonces la ecuaciΓ³n diferencial es exacta Buscando la funciΓ³n de π(π₯; π¦) Desarrollando por integrales parciales respecto a βyβ de la siguiente integral β«(π₯ β3 π¦ 2 β 4π₯ β1 )ππ¦ β π₯ β3 β«(π¦ 2 )ππ¦ β 4π₯ β1 β« ππ¦ β π(π₯; π¦) =
π₯ β3 π¦ 3 3
β 4π₯ β1 π¦ + π(π₯)
donde π(π₯) es la constante
Haciendo derivada parcial de la funciΓ³n respecto al βxβ π(π₯; π¦) = ππ₯ = β3
π₯ β4 π¦ 3 3
π₯ β3 π¦ 3 3
β 4π₯ β1 π¦ + π(π₯)
+ 4π₯ β2 π¦ + πβ²(π₯)
ππ₯ = βπ₯ β4 π¦ 3 + 4π₯ β2 π¦ + πβ²(π₯) Igualando βπ₯ β4 π¦ 3 + 4π₯ β2 π¦ + πβ² (π₯) = π₯ 2 β 2π₯ + 2 β π¦ 3 π₯ β4 + 4π₯ β2 π¦ πβ² (π₯) = π₯ 2 β 2π₯ + 2
β β« πβ² (π₯) = β«(π₯ 2 β 2π₯ + 2)ππ₯
π(π₯) = β« π₯ 2 ππ₯ β 2 β« π₯ππ₯ + 2 β« ππ₯ π(π₯) =
π₯3 3
β π₯ 2 + 2π₯
π(π₯) Reemplazando en la funciΓ³n de π(π₯; π¦) π(π₯; π¦) =
π₯ β3 π¦ 3 3
β 4π₯ β1 π¦ +
π₯3 3
β π₯ 2 + 2π₯
Finalmente igualamos el constante βCβ π₯ β3 π¦ 3 3
β 4π₯ β1 π¦ +
π₯2 3
β π₯ 2 + 2π₯ = πΆ
β΄
π¦3 3π₯ β3
π¦
β4π₯ +
π₯3 3
β π₯ 2 + 2π₯ = πΆ
24). π¦Β΄ + 1 =
π¦Β΄ + 1 =
(π₯ + π¦)π (π₯ + π¦)π + (π₯ + π¦)π
(π₯ + π¦)π (π₯ + π¦)π + (π₯ + π¦)π
πππππ: π₯ + π¦ = π§
ππ¦ π§π = π β1 ππ₯ π§ + π§π
ππ₯ + ππ¦ = ππ§ ππ¦ ππ§ = β1 ππ₯ ππ₯
ππ§ π§π β1= π β1 ππ₯ π§ + π§π π§π π§π + π§π ππ§ = π ππ₯ β ( ) ππ§ β ππ₯ = 0 π§ + π§π π§π β«(
π§π + π§π ) ππ§ β β« ππ₯ = β« 0 π§π
β« π§ πβπ ππ§ + β« π§ πβπ ππ§ β π₯ = πΆ (π§)πβπ+1 (π§)πβπ+1 + βπ₯ =0 πβπ+1 πβπ+1 ππππππππ π ππ πππ ππ’ππ π‘π
(π₯ + π¦)πβπ+1 (π₯ + π¦)πβπ+1 + +πΆ = π₯ πβπ+1 πβπ+1
25. (πππ + ππ )π
π β ππππ π
π = π Hacienda un cambio de variable: πππ₯ + π¦ 3 = π’ 1 π₯
ππ¦
ππ’
+ 3π¦ 2 (ππ₯ ) = ππ₯
ππ¦ ππ₯
=
ππ’ 1 β ) ππ₯ π₯ 3π¦ 2
(
Reemplazando:
(πππ₯+π¦ 3 )
ππ¦
= ππ₯
3π₯π¦ 2 (π’) 3π₯π¦ 2 π’ π₯
=
(
ππ’ 1 β ) ππ₯ π₯ 3π¦ 2
1
ππ’
+ π₯ = ππ₯
ππ₯
ππ’
= (π’+1)
π₯
β«
ππ₯
ππ’
= β« (π’+1)
π₯
πππ₯ = ln(π’ + 1) π₯ =π’+1 Remplazando por su valor original: π₯ = πππ₯ + π¦ 3 + 1 π¦ 3 = π₯ β πππ₯ β 1
26. (ππ + ππππππ π + ππππ)π
π + (πππ πππ + π)π
π = π Factorizamos: β
(π₯π¦+π¦πππ¦(2π₯πππ¦+1)) π₯(2π₯πππ¦+1)
ππ¦
= ππ₯
Hacienda un cambio de variable: 2π₯πππ¦ + 1 = π’ 1
ππ¦
ππ’
2π₯ π¦ (ππ₯ ) + 2πππ¦ = ππ₯ ππ¦ ππ₯
=
π¦(
ππ’ β2πππ¦) ππ₯
2π₯
Reemplazando: β β
(π₯π¦+π¦πππ¦(π’)) π₯(π’) 2(π₯+πππ¦(π’)) π’
=
π’ π’
ππ’ β2πππ¦) ππ₯
2π₯
ππ’
= ππ₯ β 2πππ¦
β2π₯β2πππ¦π’+2πππ¦π’ β2π₯
π¦(
ππ’
= ππ₯
ππ’
= ππ₯
β2π₯ππ₯ = π’ππ’ β« β2π₯ππ₯ = β« π’ππ’
β2
π₯2 2
=
π’2 2
Remplazando por su valor original: π = 2π₯ 2 + π’2 π = 2π₯ 2 + (2π₯πππ¦ + 1)2
ππ. π β ππβ² = π(π + ππ πβ² ) SOLUCION: π¦βπ₯
ππ¦ ππ¦ = π + ππ₯ 2 ππ₯ ππ₯
π¦βπ =π₯
ππ¦ ππ¦ + ππ₯ 2 ππ₯ ππ₯
π¦ β π = (π₯ β ππ₯ 2 )
ππ¦ ππ₯
π¦βπ ππ¦ = π₯ + ππ₯ 2 ππ₯ 1 1 ππ₯ = ππ¦ π₯ + ππ₯ 2 π¦βπ β« β«
1 1 ππ₯ = β« ππ¦ π₯ + ππ₯ 2 π¦βπ
1 1 ππ₯ = β« ππ¦ π₯(ππ₯ + 1) π¦βπ
ππ₯ + 1 = π’
π¦βπ =π’
ππ’ = πππ₯
ππ’ = ππ¦
1 π
1
ππ’ = ππ₯
β« π₯ ππ₯ = ln(π₯)
1 π₯ = (π’ β 1)( ) π β«
1
1 1 ( )ππ’ = β« ππ’ 1 π’ (π’ β 1) ( ) (π’) 2 2
β« β«( β«
1 ππ’ = ln(π’) (π’)(π’ β 1)
1 1 β ) ππ’ = ln(π¦ β π) π’β1 π’
1 1 ππ’ β β« ππ’ = ln(π¦ β π) π’β1 π’
ln(π’ β 1) β ln(π’) = ln(π¦ β π)
ln(ππ₯ + 1 β 1) β ln(ππ₯ + 1) = ln(π¦ β π) ππ₯ ππ = ln(π¦ β π) ππ₯ + 1 ππ₯ =π¦βπ ππ₯ + 1 ππ₯ + π = π¦ π
πΈππππΈπππ΄. ππ₯ + 1
ππ. (ππ + ππ )π
π + ππβ(ππ β ππ )π
π = π (π2 + π¦Β²)ππ₯ = β2π₯β(ππ₯ β π₯Β²)ππ¦ β
π2 + π¦ 2 2π₯βππ₯ β π₯ 2
1 2π₯β(ππ₯ β π₯ 2 ) β«
1 2π₯β(ππ₯ β π₯ 2 )
=
ππ₯ = β
ππ¦ ππ₯
1 ππ¦ π2 + π¦Β²
ππ₯ = β β«
1 ππ¦ π2 + π¦Β²
1 1 1 β« ππ₯ = β β« ππ¦ 2 π₯β(β(π₯ 2 β ππ₯)) π2 + π¦Β² 1 β« 2 1 β« 2
1 1 ππ₯ = β β« ππ¦ π π 2 π2 + π¦Β² π₯β(β((π₯ β )Β² β ( ) )) 2 2 1 1
π 2 πΒ² π₯β(β (π₯ β ) + ( ) ) 2 4
1 β« 2
ππ₯ = β β«
1 ππ¦ π2 + π¦Β²
1 1 ππ₯ = β β« 2 ππ¦ (2π₯ β π)Β² πΒ² π + π¦Β² π₯β(β + ) 4 4 1 1 1 β« ππ₯ = β β« 2 ππ¦ 2 π₯(1)β(β(2π₯ β π)2 + πΒ²) π + π¦Β² 2
β«
1 π₯β(β(2π₯ β π)2 + πΒ²)
ππ₯ = β β«
1 ππ¦ π2 + π¦Β²
2π₯ β π = π’ 1 2
π’=
ππ’ = ππ₯
π₯=
π¦ π
πππ’ = ππ¦
π’+π
π¦ = ππ’
2
β«
1
1 1 ππ’ = β β« 2 πππ’ 1 2 π + (ππ’)Β² 2 (π’ + π)( )β(β(π’) + πΒ²) 2 1 1 β« ππ’ = β β« πππ’ π2 + πΒ²π’Β² (π’ + π)β(π2 β π’Β²) 1
β«
(π’ + π)β(π2 β π’Β²) β«
ππ’ = β β«
1 π2 (π’2 + 1)
πππ’
1 1 ππ’ = β β« ππ’ π π’2 + 1 (π’ + π)β(π2 β π’Β²)
β«
1
1
1 π¦ ππ’ = β arctan ( ) π π (π’ + π)β(π2 β π’Β²)
π’ π π’π π‘ππ‘π’ππππππ : π’ = ππ ππ(π£); π£ = ππππ ππ ( ) ππ’ = acos(π£) ππ£ π β«
acos(π£)
1 π¦ ππ£ = β arctan ( ) π π (ππ ππ(π£) + π)β(π2 β (ππ ππ(π£))Β²) π2 β πΒ²π ππ2 (π£) = πΒ²πππ Β²(π£)
β«
1 π¦ ππ£ = β arctan( ) π π (ππ ππ(π£) + π)β(πΒ²πππ Β²(π£))
β«
acos(π£)
acos(π£) 1 π¦ ππ£ = β arctan( ) (ππ ππ(π£) + π)(ππππ (π£)) π π β«
1 1 π¦ ππ£ = β arctan( ) (ππ ππ(π£) + π) π π
1 1 1 π¦ β« ππ£ = β arctan( ) π (π ππ(π£) + 1) π π
1 1 1 π¦ β« ππ£ = β arctan ( ) π 2π ππ(π£)cos(π£) + 1 π π 2 2 1 1 1 π¦ β« ππ£ = β arctan ( ) π£ π π π cos ( ) π£ π£ 2 +1 2π ππ( )cos( ) 2 2 cos(π£) 2 1 1 1 π¦ β« ππ£ = β arctan ( ) π 2π‘π (π£) cosΒ²(π£) + 1 π π 2 2 1 π£ cosΒ²( ) 1 1 π¦ 2 β« ππ£ = β arctan ( ) π 2π‘π (π£) cosΒ²(π£) + 1 π π 2 2 π£ cosΒ²( ) 2 π£ π ππΒ²( ) 1 1 π¦ 2 β« ππ£ = β arctan( ) 1 π 2π‘π (π£) + π π π£ 2 πππ Β²( ) 2 1 π£ 2 = π‘π ( )+1 π£ 2 πππ Β²( ) 2 π£ π ππΒ²( ) 1 1 π¦ 2 β« ππ£ = β arctan ( ) π 2π‘π (π£) + tg 2 (π£) + 1 π π 2 2 π£ π ππΒ²( ) 1 2 ππ£ = β 1 arctan(π¦) β« π£ π (π‘π + 1)Β² π π 2 π£ 2 π€ = π‘ππ + 1 ; ππ£ = π£ ππ€ 2 π ππΒ²( ) 2 π£ 1 π ππΒ²(2) 2 1 π¦ β« ππ€ = β arctan ( ) π π π (π€)Β² π ππΒ²(π£) 2
2 1 1 π¦ β« ππ€ = β arctan( ) π (π€)Β² π π
2
1
π¦
β« π€ β2 ππ€ = β π arctan(π) π 2 π€ β1 1 π¦ β = β arctan( ) π β1 π π 2 1 1 π¦ β β = β arctan( ) π π€ π π 2 1 1 π¦ β β = β arctan( ) π£ π tan( ) + 1 π π 2 2 1 1 π¦ β β = β arctan ( ) π’ π π π ππππ ππ( ) 2 )+1 tan( 2 2 1 1 π¦ β β = β arctan( ) π π π π’2 π (1 β β1 β 2 ) π +1 π’ 2 1 1 π¦ β β = β arctan( ) π π π (2π₯ β π)2 π (1 β β1 β ) π2 +1 2π₯ β π β(ππ₯ β π₯ 2 ) 1 π¦ β = β arctan( ) ππ₯ π π π‘ππ
β(ππ₯ β π₯ 2 ) 1 π¦ = (tan)arctan( ) ππ₯ π π
β(ππ₯ β π₯ 2 ) 1 π¦ π‘ππ = (tan)arctan( ) ππ₯ π π β(ππ₯ β π₯ 2 ) 1 π¦ π‘ππ = β( ) ππ₯ π π
β(ππ₯ β π₯ 2 ) πΒ²π‘ππ =π¦ ππ₯ β(ππ₯ β π₯ 2 ) ππ‘ππ =π¦ π₯ ππ₯ β π₯ 2 ππ‘ππβ( )=π¦ π₯2 ππ‘ππβ(
π₯(π β π₯) )=π¦ π₯2
ππ‘ππβ(
(π β π₯) )=π¦ π₯
π
ππ‘ππβ( β 1) = π¦ RESPUESTA π₯
EJERCICIO NΒ° 29 π + π πβ π πΒ΄ + πππ ( ) = πππ ( ) π π ππ¦ π₯ + π¦ π₯β π¦ + π ππ ( ) = π ππ ( ) ππ₯ 2 2 ππ¦ π₯ π¦ π₯ π¦ + π ππ ( + ) = π ππ ( β ) ππ₯ 2 2 2 2 ππ¦ π₯ π¦ π₯ π¦ = π ππ ( β ) β π ππ ( + ) ππ₯ 2 2 2 2 APLICAMOS FORMULA DE ΓNGULO DOBLE COMPUESTO π ππ(π₯ + π¦) = π ππ(π₯) β cos(π¦) + cos(π₯) β π ππ(π¦) π ππ(π₯ β π¦) = π ππ(π₯) β cos(π¦) β cos(π₯) β π ππ(π¦)
ππ¦ π₯ π¦ π₯ π¦ π₯ π¦ π₯ π¦ = (π ππ ( ) β cos ( ) β cos ( ) β π ππ ( )) β (π ππ ( ) β cos ( ) + cos ( ) β π ππ ( )) ππ₯ 2 2 2 2 2 2 2 2 ππ¦ π₯ π¦ π₯ π¦ π₯ π¦ π₯ π¦ + (π ππ ( ) β cos ( ) + cos ( ) β π ππ ( )) β (π ππ ( ) β cos ( ) β cos ( ) β π ππ ( )) ππ₯ 2 2 2 2 2 2 2 2 =0 ππ¦ π₯ π¦ π₯ π¦ + cos ( ) β π ππ ( ) β (β cos ( ) β π ππ ( )) = 0 ππ₯ 2 2 2 2 ππ¦ π₯ π¦ + 2 (cos ( ) β π ππ ( )) = 0 ππ₯ 2 2
ππ¦ π₯ π¦ = β2 β cos ( ) β π ππ ( ) ππ₯ 2 2 ππ¦ π₯ π¦ = βcos (2) β ππ₯ 2π ππ (2) SEPARAMOS EN DOS PARTES A Y B ππ¦ π΄= π¦ 2π ππ (2) π₯ B = βcos ( ) β ππ₯ 2 DESARROLLANDO LA INTEGRAL DE A ππ¦ β« π¦ 2π ππ ( ) 2
HACEMOS UN CAMBIO DE VARIABLE π¦ π’= 2 π·πΈπ
πΌππ΄πππ 2 β ππ’ = ππ¦ 1 2 β ππ’ β β« 2 π ππ(π’) π»π΄πΆπΈπππ πππ
π πΆπ΄ππ΅πΌπ π·πΈ ππ΄π
πΌπ΄π΅πΏπΈ π’ π£ = tan ( ) 2 π·πΈπ
πΌππ΄πππ π’ π ππ 2 (2) β ππ’ ππ£ = 2 π·πΈπππΈπ½π΄πππ ππ’ π’ ππ’ = πππ 2 ( ) β 2 β ππ£ 2 π
πΈπΈπππΏπ΄ππ΄πππ π’ πππ 2 (2) β 2 β ππ£ 1 β 2ββ« 2 π ππ(π’) πΉππ
πππΏπ΄ π·πΈ π΄ππΊππΏπ π·ππ΅πΏπΈ π ππ(2π₯) = π ππ(π₯) β cos(π₯) π’ πππ 2 (2) β 2 β ππ£ β« π’ π’ π ππ (2) β cos (2) 1 β 2 β ππ£ β« π’ tan ( ) 2 π’ β« ctg ( ) β 2 β ππ£ 2
1 2 β β« β ππ£ + πΆ v π΄ππΏπΆπ΄ππ·π πΏπ΄ πΌπππΈπΊπ
π΄πΏ 2 β πΏπ(π) π₯ 2 β πΏπ (tan ( )) + πΆ 4
DESARROLLANDO LA INTEGRAL DE B π₯ β« βcos ( ) β ππ₯ 2 π΄ππΏπΌπΆπ΄ππ·π πΉππ
πππΏπ΄ π·πΈ π΄ππΊππΏπ π·ππ΅πΏπΈ π₯ 1 + cos(π₯) cos ( ) = β 2 2 1 + cos(π₯) β« ββ β ππ₯ 2 1 β β« ββ1 + cos(π₯) β ππ₯ 4 1 ββ1 + cos(π₯) β β1 β cos(π₯) ββ« β ππ₯ 4 β1 β cos(π₯) 1 β(1 β cos2 (π₯)) β ββ« β ππ₯ 4 β1 β cos(π₯) π΄ππΏπΌπΆπ΄ππ·π πΌπ·πΈππΌπ·π΄π·πΈπ ππΌππ΄πΊππ
πΌπΆπ΄π π ππ2 + πππ 2 = 1 π ππ2 = 1 β πππ 2 π
πΈπΈπππΏπ΄ππ΄πππ 1 βπ ππ2 (π₯) β ββ« β ππ₯ 4 β1 β cos(π₯) β1 π ππ(π₯) ββ« β ππ₯ 4 β1 β cos(π₯) 1 β1 β β« π ππ(π₯) β (1 β cos(π₯))2 ππ₯ 4 π΄ππΏπΌπΆπ΄ππ·π πΉΓπ
πππΏπ΄ πΌπππΈπ·πΌπ΄ππ΄ π·πΈ πΌπππΈπΊπ
π΄πΏπΈπ 1 β1 β β« π ππ(π₯) β (1 β cos(π₯))2 ππ₯ 4 β1
1 β(1 β cos(π₯)) 2 +1 β β( + πΆ) β1 4 2 +1
1 β (2β1 β cos(π₯) + πΆ) 4
SUMANOS A Y B π₯ 1 2 β πΏπ (tan ( )) + β (2β1 β cos(π₯) + πΆ) 4 4 π₯ 1 2 β πΏπ (tan ( )) + β (β1 β cos(π₯)) + πΆ 4 2