Se da la desigualdad:
log ( x ) cos ( x ) + 1 2 x 2 + 3 10 > 0 \frac{\sqrt{\log{\left(x \right)}} \cos{\left(x \right)} + 1}{2 x^{2} + \frac{3}{10}} > 0 2 x 2 + 10 3 log ( x ) cos ( x ) + 1 > 0 Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
log ( x ) cos ( x ) + 1 2 x 2 + 3 10 = 0 \frac{\sqrt{\log{\left(x \right)}} \cos{\left(x \right)} + 1}{2 x^{2} + \frac{3}{10}} = 0 2 x 2 + 10 3 log ( x ) cos ( x ) + 1 = 0 Resolvemos:
x 1 = 71.1912792889667 x_{1} = 71.1912792889667 x 1 = 71.1912792889667 x 2 = 98.474533286571 x_{2} = 98.474533286571 x 2 = 98.474533286571 x 3 = 39.81790749774 x_{3} = 39.81790749774 x 3 = 39.81790749774 x 4 = 21.0304855439734 x_{4} = 21.0304855439734 x 4 = 21.0304855439734 x 5 = 16.6398016669406 x_{5} = 16.6398016669406 x 5 = 16.6398016669406 x 6 = − 14.5888124902477 + 0.226872717278656 i x_{6} = -14.5888124902477 + 0.226872717278656 i x 6 = − 14.5888124902477 + 0.226872717278656 i x 7 = 92.1875094576666 x_{7} = 92.1875094576666 x 7 = 92.1875094576666 x 8 = 10.281291113331 x_{8} = 10.281291113331 x 8 = 10.281291113331 x 9 = − 39.7038117619331 + 0.17233651300255 i x_{9} = -39.7038117619331 + 0.17233651300255 i x 9 = − 39.7038117619331 + 0.17233651300255 i x 10 = − 96.2321309612412 + 0.137179335755008 i x_{10} = -96.2321309612412 + 0.137179335755008 i x 10 = − 96.2321309612412 + 0.137179335755008 i x 11 = − 45.9837737712157 + 0.165738764495262 i x_{11} = -45.9837737712157 + 0.165738764495262 i x 11 = − 45.9837737712157 + 0.165738764495262 i x 12 = 52.3629208376902 x_{12} = 52.3629208376902 x 12 = 52.3629208376902 x 13 = − 8.30976228954732 + 0.265285357278091 i x_{13} = -8.30976228954732 + 0.265285357278091 i x 13 = − 8.30976228954732 + 0.265285357278091 i x 14 = 73.3238866173867 x_{14} = 73.3238866173867 x 14 = 73.3238866173867 x 15 = 33.5494926868552 x_{15} = 33.5494926868552 x 15 = 33.5494926868552 x 16 = 2.89542674062072 x_{16} = 2.89542674062072 x 16 = 2.89542674062072 x 17 = 41.8676121416725 x_{17} = 41.8676121416725 x 17 = 41.8676121416725 x 18 = 96.3054969471318 x_{18} = 96.3054969471318 x 18 = 96.3054969471318 x 19 = − 2.00403434136006 + 0.381685209669179 i x_{19} = -2.00403434136006 + 0.381685209669179 i x 19 = − 2.00403434136006 + 0.381685209669179 i x 20 = 46.0893682722708 x_{20} = 46.0893682722708 x 20 = 46.0893682722708 x 21 = − 33.4242689303608 − 0.180502407081655 i x_{21} = -33.4242689303608 - 0.180502407081655 i x 21 = − 33.4242689303608 − 0.180502407081655 i x 22 = 85.900110905374 x_{22} = 85.900110905374 x 22 = 85.900110905374 x 23 = 67.0348489150335 x_{23} = 67.0348489150335 x 23 = 67.0348489150335 x 24 = 48.1617912315399 x_{24} = 48.1617912315399 x 24 = 48.1617912315399 x 25 = − 20.8667854490919 + 0.205372682871723 i x_{25} = -20.8667854490919 + 0.205372682871723 i x 25 = − 20.8667854490919 + 0.205372682871723 i x 26 = 35.5707249305613 x_{26} = 35.5707249305613 x 26 = 35.5707249305613 x 27 = 77.4690706575254 x_{27} = 77.4690706575254 x 27 = 77.4690706575254 x 28 = − 27.1452347681677 + 0.191019151516423 i x_{28} = -27.1452347681677 + 0.191019151516423 i x 28 = − 27.1452347681677 + 0.191019151516423 i x 29 = − 64.8254962012094 + 0.151548289135052 i x_{29} = -64.8254962012094 + 0.151548289135052 i x 29 = − 64.8254962012094 + 0.151548289135052 i x 30 = − 71.1065236432573 + 0.148006153381578 i x_{30} = -71.1065236432573 + 0.148006153381578 i x 30 = − 71.1065236432573 + 0.148006153381578 i x 31 = − 83.6690686014435 + 0.142043989123022 i x_{31} = -83.6690686014435 + 0.142043989123022 i x 31 = − 83.6690686014435 + 0.142043989123022 i x 32 = − 89.9505434161105 − 0.139497269580281 i x_{32} = -89.9505434161105 - 0.139497269580281 i x 32 = − 89.9505434161105 − 0.139497269580281 i x 33 = − 77.3877222898321 + 0.144862032629662 i x_{33} = -77.3877222898321 + 0.144862032629662 i x 33 = − 77.3877222898321 + 0.144862032629662 i x 34 = 79.612267055827 x_{34} = 79.612267055827 x 34 = 79.612267055827 x 35 = − 77.3877222898321 − 0.144862032629662 i x_{35} = -77.3877222898321 - 0.144862032629662 i x 35 = − 77.3877222898321 − 0.144862032629662 i x 36 = 60.7449902944826 x_{36} = 60.7449902944826 x 36 = 60.7449902944826 x 37 = 90.0262672782923 x_{37} = 90.0262672782923 x 37 = 90.0262672782923 x 38 = 3.6362645418106 x_{38} = 3.6362645418106 x 38 = 3.6362645418106 x 39 = − 33.4242689303608 + 0.180502407081655 i x_{39} = -33.4242689303608 + 0.180502407081655 i x 39 = − 33.4242689303608 + 0.180502407081655 i x 40 = 83.7474330794998 x_{40} = 83.7474330794998 x 40 = 83.7474330794998 x 41 = 27.2858437418209 x_{41} = 27.2858437418209 x 41 = 27.2858437418209 x 42 = − 52.2640794943649 + 0.160251249342434 i x_{42} = -52.2640794943649 + 0.160251249342434 i x 42 = − 52.2640794943649 + 0.160251249342434 i x 43 = 54.4540818737093 x_{43} = 54.4540818737093 x 43 = 54.4540818737093 x 44 = 58.6379866203864 x_{44} = 58.6379866203864 x 44 = 58.6379866203864 x 45 = − 58.5446692207647 + 0.155585268948379 i x_{45} = -58.5446692207647 + 0.155585268948379 i x 45 = − 58.5446692207647 + 0.155585268948379 i x 46 = 14.7922764129932 x_{46} = 14.7922764129932 x 46 = 14.7922764129932 x 47 = − 45.9837737712157 − 0.165738764495262 i x_{47} = -45.9837737712157 - 0.165738764495262 i x 47 = − 45.9837737712157 − 0.165738764495262 i x 48 = 64.9141910839444 x_{48} = 64.9141910839444 x 48 = 64.9141910839444 x 49 = 8.6039855648616 x_{49} = 8.6039855648616 x 49 = 8.6039855648616 x 50 = 22.9616469753377 x_{50} = 22.9616469753377 x 50 = 22.9616469753377 x 51 = − 89.9505434161105 + 0.139497269580281 i x_{51} = -89.9505434161105 + 0.139497269580281 i x 51 = − 89.9505434161105 + 0.139497269580281 i x 52 = 29.2696879165931 x_{52} = 29.2696879165931 x 52 = 29.2696879165931 Descartamos las soluciones complejas:
x 1 = 71.1912792889667 x_{1} = 71.1912792889667 x 1 = 71.1912792889667 x 2 = 98.474533286571 x_{2} = 98.474533286571 x 2 = 98.474533286571 x 3 = 39.81790749774 x_{3} = 39.81790749774 x 3 = 39.81790749774 x 4 = 21.0304855439734 x_{4} = 21.0304855439734 x 4 = 21.0304855439734 x 5 = 16.6398016669406 x_{5} = 16.6398016669406 x 5 = 16.6398016669406 x 6 = 92.1875094576666 x_{6} = 92.1875094576666 x 6 = 92.1875094576666 x 7 = 10.281291113331 x_{7} = 10.281291113331 x 7 = 10.281291113331 x 8 = 52.3629208376902 x_{8} = 52.3629208376902 x 8 = 52.3629208376902 x 9 = 73.3238866173867 x_{9} = 73.3238866173867 x 9 = 73.3238866173867 x 10 = 33.5494926868552 x_{10} = 33.5494926868552 x 10 = 33.5494926868552 x 11 = 2.89542674062072 x_{11} = 2.89542674062072 x 11 = 2.89542674062072 x 12 = 41.8676121416725 x_{12} = 41.8676121416725 x 12 = 41.8676121416725 x 13 = 96.3054969471318 x_{13} = 96.3054969471318 x 13 = 96.3054969471318 x 14 = 46.0893682722708 x_{14} = 46.0893682722708 x 14 = 46.0893682722708 x 15 = 85.900110905374 x_{15} = 85.900110905374 x 15 = 85.900110905374 x 16 = 67.0348489150335 x_{16} = 67.0348489150335 x 16 = 67.0348489150335 x 17 = 48.1617912315399 x_{17} = 48.1617912315399 x 17 = 48.1617912315399 x 18 = 35.5707249305613 x_{18} = 35.5707249305613 x 18 = 35.5707249305613 x 19 = 77.4690706575254 x_{19} = 77.4690706575254 x 19 = 77.4690706575254 x 20 = 79.612267055827 x_{20} = 79.612267055827 x 20 = 79.612267055827 x 21 = 60.7449902944826 x_{21} = 60.7449902944826 x 21 = 60.7449902944826 x 22 = 90.0262672782923 x_{22} = 90.0262672782923 x 22 = 90.0262672782923 x 23 = 3.6362645418106 x_{23} = 3.6362645418106 x 23 = 3.6362645418106 x 24 = 83.7474330794998 x_{24} = 83.7474330794998 x 24 = 83.7474330794998 x 25 = 27.2858437418209 x_{25} = 27.2858437418209 x 25 = 27.2858437418209 x 26 = 54.4540818737093 x_{26} = 54.4540818737093 x 26 = 54.4540818737093 x 27 = 58.6379866203864 x_{27} = 58.6379866203864 x 27 = 58.6379866203864 x 28 = 14.7922764129932 x_{28} = 14.7922764129932 x 28 = 14.7922764129932 x 29 = 64.9141910839444 x_{29} = 64.9141910839444 x 29 = 64.9141910839444 x 30 = 8.6039855648616 x_{30} = 8.6039855648616 x 30 = 8.6039855648616 x 31 = 22.9616469753377 x_{31} = 22.9616469753377 x 31 = 22.9616469753377 x 32 = 29.2696879165931 x_{32} = 29.2696879165931 x 32 = 29.2696879165931 Las raíces dadas
x 11 = 2.89542674062072 x_{11} = 2.89542674062072 x 11 = 2.89542674062072 x 23 = 3.6362645418106 x_{23} = 3.6362645418106 x 23 = 3.6362645418106 x 30 = 8.6039855648616 x_{30} = 8.6039855648616 x 30 = 8.6039855648616 x 7 = 10.281291113331 x_{7} = 10.281291113331 x 7 = 10.281291113331 x 28 = 14.7922764129932 x_{28} = 14.7922764129932 x 28 = 14.7922764129932 x 5 = 16.6398016669406 x_{5} = 16.6398016669406 x 5 = 16.6398016669406 x 4 = 21.0304855439734 x_{4} = 21.0304855439734 x 4 = 21.0304855439734 x 31 = 22.9616469753377 x_{31} = 22.9616469753377 x 31 = 22.9616469753377 x 25 = 27.2858437418209 x_{25} = 27.2858437418209 x 25 = 27.2858437418209 x 32 = 29.2696879165931 x_{32} = 29.2696879165931 x 32 = 29.2696879165931 x 10 = 33.5494926868552 x_{10} = 33.5494926868552 x 10 = 33.5494926868552 x 18 = 35.5707249305613 x_{18} = 35.5707249305613 x 18 = 35.5707249305613 x 3 = 39.81790749774 x_{3} = 39.81790749774 x 3 = 39.81790749774 x 12 = 41.8676121416725 x_{12} = 41.8676121416725 x 12 = 41.8676121416725 x 14 = 46.0893682722708 x_{14} = 46.0893682722708 x 14 = 46.0893682722708 x 17 = 48.1617912315399 x_{17} = 48.1617912315399 x 17 = 48.1617912315399 x 8 = 52.3629208376902 x_{8} = 52.3629208376902 x 8 = 52.3629208376902 x 26 = 54.4540818737093 x_{26} = 54.4540818737093 x 26 = 54.4540818737093 x 27 = 58.6379866203864 x_{27} = 58.6379866203864 x 27 = 58.6379866203864 x 21 = 60.7449902944826 x_{21} = 60.7449902944826 x 21 = 60.7449902944826 x 29 = 64.9141910839444 x_{29} = 64.9141910839444 x 29 = 64.9141910839444 x 16 = 67.0348489150335 x_{16} = 67.0348489150335 x 16 = 67.0348489150335 x 1 = 71.1912792889667 x_{1} = 71.1912792889667 x 1 = 71.1912792889667 x 9 = 73.3238866173867 x_{9} = 73.3238866173867 x 9 = 73.3238866173867 x 19 = 77.4690706575254 x_{19} = 77.4690706575254 x 19 = 77.4690706575254 x 20 = 79.612267055827 x_{20} = 79.612267055827 x 20 = 79.612267055827 x 24 = 83.7474330794998 x_{24} = 83.7474330794998 x 24 = 83.7474330794998 x 15 = 85.900110905374 x_{15} = 85.900110905374 x 15 = 85.900110905374 x 22 = 90.0262672782923 x_{22} = 90.0262672782923 x 22 = 90.0262672782923 x 6 = 92.1875094576666 x_{6} = 92.1875094576666 x 6 = 92.1875094576666 x 13 = 96.3054969471318 x_{13} = 96.3054969471318 x 13 = 96.3054969471318 x 2 = 98.474533286571 x_{2} = 98.474533286571 x 2 = 98.474533286571 son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
x 0 < x 11 x_{0} < x_{11} x 0 < x 11 Consideremos, por ejemplo, el punto
x 0 = x 11 − 1 10 x_{0} = x_{11} - \frac{1}{10} x 0 = x 11 − 10 1 =
− 1 10 + 2.89542674062072 - \frac{1}{10} + 2.89542674062072 − 10 1 + 2.89542674062072 =
2.79542674062072 2.79542674062072 2.79542674062072 lo sustituimos en la expresión
log ( x ) cos ( x ) + 1 2 x 2 + 3 10 > 0 \frac{\sqrt{\log{\left(x \right)}} \cos{\left(x \right)} + 1}{2 x^{2} + \frac{3}{10}} > 0 2 x 2 + 10 3 log ( x ) cos ( x ) + 1 > 0 log ( 2.79542674062072 ) cos ( 2.79542674062072 ) + 1 3 10 + 2 ⋅ 2.7954267406207 2 2 > 0 \frac{\sqrt{\log{\left(2.79542674062072 \right)}} \cos{\left(2.79542674062072 \right)} + 1}{\frac{3}{10} + 2 \cdot 2.79542674062072^{2}} > 0 10 3 + 2 ⋅ 2.7954267406207 2 2 log ( 2.79542674062072 ) cos ( 2.79542674062072 ) + 1 > 0 0.00290341311615150 > 0 significa que una de las soluciones de nuestra ecuación será con:
x < 2.89542674062072 x < 2.89542674062072 x < 2.89542674062072 _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____ _____
\ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ /
-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------
x11 x23 x30 x7 x28 x5 x4 x31 x25 x32 x10 x18 x3 x12 x14 x17 x8 x26 x27 x21 x29 x16 x1 x9 x19 x20 x24 x15 x22 x6 x13 x2 Recibiremos otras soluciones de la desigualdad pasando al polo siguiente etc.
etc.
Respuesta:
x < 2.89542674062072 x < 2.89542674062072 x < 2.89542674062072 x > 3.6362645418106 ∧ x < 8.6039855648616 x > 3.6362645418106 \wedge x < 8.6039855648616 x > 3.6362645418106 ∧ x < 8.6039855648616 x > 10.281291113331 ∧ x < 14.7922764129932 x > 10.281291113331 \wedge x < 14.7922764129932 x > 10.281291113331 ∧ x < 14.7922764129932 x > 16.6398016669406 ∧ x < 21.0304855439734 x > 16.6398016669406 \wedge x < 21.0304855439734 x > 16.6398016669406 ∧ x < 21.0304855439734 x > 22.9616469753377 ∧ x < 27.2858437418209 x > 22.9616469753377 \wedge x < 27.2858437418209 x > 22.9616469753377 ∧ x < 27.2858437418209 x > 29.2696879165931 ∧ x < 33.5494926868552 x > 29.2696879165931 \wedge x < 33.5494926868552 x > 29.2696879165931 ∧ x < 33.5494926868552 x > 35.5707249305613 ∧ x < 39.81790749774 x > 35.5707249305613 \wedge x < 39.81790749774 x > 35.5707249305613 ∧ x < 39.81790749774 x > 41.8676121416725 ∧ x < 46.0893682722708 x > 41.8676121416725 \wedge x < 46.0893682722708 x > 41.8676121416725 ∧ x < 46.0893682722708 x > 48.1617912315399 ∧ x < 52.3629208376902 x > 48.1617912315399 \wedge x < 52.3629208376902 x > 48.1617912315399 ∧ x < 52.3629208376902 x > 54.4540818737093 ∧ x < 58.6379866203864 x > 54.4540818737093 \wedge x < 58.6379866203864 x > 54.4540818737093 ∧ x < 58.6379866203864 x > 60.7449902944826 ∧ x < 64.9141910839444 x > 60.7449902944826 \wedge x < 64.9141910839444 x > 60.7449902944826 ∧ x < 64.9141910839444 x > 67.0348489150335 ∧ x < 71.1912792889667 x > 67.0348489150335 \wedge x < 71.1912792889667 x > 67.0348489150335 ∧ x < 71.1912792889667 x > 73.3238866173867 ∧ x < 77.4690706575254 x > 73.3238866173867 \wedge x < 77.4690706575254 x > 73.3238866173867 ∧ x < 77.4690706575254 x > 79.612267055827 ∧ x < 83.7474330794998 x > 79.612267055827 \wedge x < 83.7474330794998 x > 79.612267055827 ∧ x < 83.7474330794998 x > 85.900110905374 ∧ x < 90.0262672782923 x > 85.900110905374 \wedge x < 90.0262672782923 x > 85.900110905374 ∧ x < 90.0262672782923 x > 92.1875094576666 ∧ x < 96.3054969471318 x > 92.1875094576666 \wedge x < 96.3054969471318 x > 92.1875094576666 ∧ x < 96.3054969471318 x > 98.474533286571 x > 98.474533286571 x > 98.474533286571