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cos2x+5sin>-2

cos2x+5sin>-2 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
cos(2*x) + 5*sin(x) > -2
$$5 \sin{\left(x \right)} + \cos{\left(2 x \right)} > -2$$
5*sin(x) + cos(2*x) > -2
Solución detallada
Se da la desigualdad:
$$5 \sin{\left(x \right)} + \cos{\left(2 x \right)} > -2$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$5 \sin{\left(x \right)} + \cos{\left(2 x \right)} = -2$$
Resolvemos:
Tenemos la ecuación
$$5 \sin{\left(x \right)} + \cos{\left(2 x \right)} = -2$$
cambiamos
$$5 \sin{\left(x \right)} + \cos{\left(2 x \right)} + 2 = 0$$
$$- 2 \sin^{2}{\left(x \right)} + 5 \sin{\left(x \right)} + 3 = 0$$
Sustituimos
$$w = \sin{\left(x \right)}$$
Es la ecuación de la forma
a*w^2 + b*w + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$w_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$w_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = -2$$
$$b = 5$$
$$c = 3$$
, entonces
D = b^2 - 4 * a * c = 

(5)^2 - 4 * (-2) * (3) = 49

Como D > 0 la ecuación tiene dos raíces.
w1 = (-b + sqrt(D)) / (2*a)

w2 = (-b - sqrt(D)) / (2*a)

o
$$w_{1} = - \frac{1}{2}$$
$$w_{2} = 3$$
hacemos cambio inverso
$$\sin{\left(x \right)} = w$$
Tenemos la ecuación
$$\sin{\left(x \right)} = w$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
O
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
, donde n es cualquier número entero
sustituimos w:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(- \frac{1}{2} \right)}$$
$$x_{1} = 2 \pi n - \frac{\pi}{6}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(3 \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(3 \right)}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(- \frac{1}{2} \right)} + \pi$$
$$x_{3} = 2 \pi n + \frac{7 \pi}{6}$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(3 \right)}$$
$$x_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(3 \right)}$$
$$x_{1} = 47.6474885794452$$
$$x_{2} = 74.8746249105567$$
$$x_{3} = 81.1578102177363$$
$$x_{4} = -27.7507351067098$$
$$x_{5} = 60.2138591938044$$
$$x_{6} = 110.479341651241$$
$$x_{7} = -19.3731546971371$$
$$x_{8} = -50.789081233035$$
$$x_{9} = -21.4675497995303$$
$$x_{10} = 112.573736753634$$
$$x_{11} = -44.5058959258554$$
$$x_{12} = -57.0722665402146$$
$$x_{13} = 43.4586983746588$$
$$x_{14} = 18.3259571459405$$
$$x_{15} = -643.502895210309$$
$$x_{16} = -34.0339204138894$$
$$x_{17} = -38.2227106186758$$
$$x_{18} = -59.1666616426078$$
$$x_{19} = 72.7802298081635$$
$$x_{20} = -13.0899693899575$$
$$x_{21} = 3.66519142918809$$
$$x_{22} = -6.80678408277789$$
$$x_{23} = -52.8834763354282$$
$$x_{24} = -65.4498469497874$$
$$x_{25} = -46.6002910282486$$
$$x_{26} = 87.4409955249159$$
$$x_{27} = -88.4881930761125$$
$$x_{28} = 24.60914245312$$
$$x_{29} = 100.007366139275$$
$$x_{30} = -31.9395253114962$$
$$x_{31} = 79.0634151153431$$
$$x_{32} = -63.3554518473942$$
$$x_{33} = 56.025068989018$$
$$x_{34} = 41.3643032722656$$
$$x_{35} = 91.6297857297023$$
$$x_{36} = 28.7979326579064$$
$$x_{37} = 93.7241808320955$$
$$x_{38} = -69.6386371545737$$
$$x_{39} = -45867.7763411866$$
$$x_{40} = 37.1755130674792$$
$$x_{41} = 53.9306738866248$$
$$x_{42} = 16.2315620435473$$
$$x_{43} = -75.9218224617533$$
$$x_{44} = -94.7713783832921$$
$$x_{45} = -78.0162175641465$$
$$x_{46} = 791.15774992903$$
$$x_{47} = 68.5914396033772$$
$$x_{48} = -82.2050077689329$$
$$x_{49} = -96.8657734856853$$
$$x_{50} = -84.2994028713261$$
$$x_{51} = 9.94837673636768$$
$$x_{52} = -0.523598775598299$$
$$x_{53} = 12.0427718387609$$
$$x_{54} = -2.61799387799149$$
$$x_{55} = 49.7418836818384$$
$$x_{56} = -71.733032256967$$
$$x_{57} = -40.317105721069$$
$$x_{58} = -8.90117918517108$$
$$x_{59} = 66.497044500984$$
$$x_{60} = 35.081117965086$$
$$x_{61} = 85.3466004225227$$
$$x_{62} = 5.75958653158129$$
$$x_{63} = -90.5825881785057$$
$$x_{64} = -239.284640448423$$
$$x_{65} = -25.6563400043166$$
$$x_{66} = 22.5147473507269$$
$$x_{67} = -101.054563690472$$
$$x_{68} = -15.1843644923507$$
$$x_{69} = 62.3082542961976$$
$$x_{70} = 30.8923277602996$$
$$x_{71} = 97.9129710368819$$
$$x_{1} = 47.6474885794452$$
$$x_{2} = 74.8746249105567$$
$$x_{3} = 81.1578102177363$$
$$x_{4} = -27.7507351067098$$
$$x_{5} = 60.2138591938044$$
$$x_{6} = 110.479341651241$$
$$x_{7} = -19.3731546971371$$
$$x_{8} = -50.789081233035$$
$$x_{9} = -21.4675497995303$$
$$x_{10} = 112.573736753634$$
$$x_{11} = -44.5058959258554$$
$$x_{12} = -57.0722665402146$$
$$x_{13} = 43.4586983746588$$
$$x_{14} = 18.3259571459405$$
$$x_{15} = -643.502895210309$$
$$x_{16} = -34.0339204138894$$
$$x_{17} = -38.2227106186758$$
$$x_{18} = -59.1666616426078$$
$$x_{19} = 72.7802298081635$$
$$x_{20} = -13.0899693899575$$
$$x_{21} = 3.66519142918809$$
$$x_{22} = -6.80678408277789$$
$$x_{23} = -52.8834763354282$$
$$x_{24} = -65.4498469497874$$
$$x_{25} = -46.6002910282486$$
$$x_{26} = 87.4409955249159$$
$$x_{27} = -88.4881930761125$$
$$x_{28} = 24.60914245312$$
$$x_{29} = 100.007366139275$$
$$x_{30} = -31.9395253114962$$
$$x_{31} = 79.0634151153431$$
$$x_{32} = -63.3554518473942$$
$$x_{33} = 56.025068989018$$
$$x_{34} = 41.3643032722656$$
$$x_{35} = 91.6297857297023$$
$$x_{36} = 28.7979326579064$$
$$x_{37} = 93.7241808320955$$
$$x_{38} = -69.6386371545737$$
$$x_{39} = -45867.7763411866$$
$$x_{40} = 37.1755130674792$$
$$x_{41} = 53.9306738866248$$
$$x_{42} = 16.2315620435473$$
$$x_{43} = -75.9218224617533$$
$$x_{44} = -94.7713783832921$$
$$x_{45} = -78.0162175641465$$
$$x_{46} = 791.15774992903$$
$$x_{47} = 68.5914396033772$$
$$x_{48} = -82.2050077689329$$
$$x_{49} = -96.8657734856853$$
$$x_{50} = -84.2994028713261$$
$$x_{51} = 9.94837673636768$$
$$x_{52} = -0.523598775598299$$
$$x_{53} = 12.0427718387609$$
$$x_{54} = -2.61799387799149$$
$$x_{55} = 49.7418836818384$$
$$x_{56} = -71.733032256967$$
$$x_{57} = -40.317105721069$$
$$x_{58} = -8.90117918517108$$
$$x_{59} = 66.497044500984$$
$$x_{60} = 35.081117965086$$
$$x_{61} = 85.3466004225227$$
$$x_{62} = 5.75958653158129$$
$$x_{63} = -90.5825881785057$$
$$x_{64} = -239.284640448423$$
$$x_{65} = -25.6563400043166$$
$$x_{66} = 22.5147473507269$$
$$x_{67} = -101.054563690472$$
$$x_{68} = -15.1843644923507$$
$$x_{69} = 62.3082542961976$$
$$x_{70} = 30.8923277602996$$
$$x_{71} = 97.9129710368819$$
Las raíces dadas
$$x_{39} = -45867.7763411866$$
$$x_{15} = -643.502895210309$$
$$x_{64} = -239.284640448423$$
$$x_{67} = -101.054563690472$$
$$x_{49} = -96.8657734856853$$
$$x_{44} = -94.7713783832921$$
$$x_{63} = -90.5825881785057$$
$$x_{27} = -88.4881930761125$$
$$x_{50} = -84.2994028713261$$
$$x_{48} = -82.2050077689329$$
$$x_{45} = -78.0162175641465$$
$$x_{43} = -75.9218224617533$$
$$x_{56} = -71.733032256967$$
$$x_{38} = -69.6386371545737$$
$$x_{24} = -65.4498469497874$$
$$x_{32} = -63.3554518473942$$
$$x_{18} = -59.1666616426078$$
$$x_{12} = -57.0722665402146$$
$$x_{23} = -52.8834763354282$$
$$x_{8} = -50.789081233035$$
$$x_{25} = -46.6002910282486$$
$$x_{11} = -44.5058959258554$$
$$x_{57} = -40.317105721069$$
$$x_{17} = -38.2227106186758$$
$$x_{16} = -34.0339204138894$$
$$x_{30} = -31.9395253114962$$
$$x_{4} = -27.7507351067098$$
$$x_{65} = -25.6563400043166$$
$$x_{9} = -21.4675497995303$$
$$x_{7} = -19.3731546971371$$
$$x_{68} = -15.1843644923507$$
$$x_{20} = -13.0899693899575$$
$$x_{58} = -8.90117918517108$$
$$x_{22} = -6.80678408277789$$
$$x_{54} = -2.61799387799149$$
$$x_{52} = -0.523598775598299$$
$$x_{21} = 3.66519142918809$$
$$x_{62} = 5.75958653158129$$
$$x_{51} = 9.94837673636768$$
$$x_{53} = 12.0427718387609$$
$$x_{42} = 16.2315620435473$$
$$x_{14} = 18.3259571459405$$
$$x_{66} = 22.5147473507269$$
$$x_{28} = 24.60914245312$$
$$x_{36} = 28.7979326579064$$
$$x_{70} = 30.8923277602996$$
$$x_{60} = 35.081117965086$$
$$x_{40} = 37.1755130674792$$
$$x_{34} = 41.3643032722656$$
$$x_{13} = 43.4586983746588$$
$$x_{1} = 47.6474885794452$$
$$x_{55} = 49.7418836818384$$
$$x_{41} = 53.9306738866248$$
$$x_{33} = 56.025068989018$$
$$x_{5} = 60.2138591938044$$
$$x_{69} = 62.3082542961976$$
$$x_{59} = 66.497044500984$$
$$x_{47} = 68.5914396033772$$
$$x_{19} = 72.7802298081635$$
$$x_{2} = 74.8746249105567$$
$$x_{31} = 79.0634151153431$$
$$x_{3} = 81.1578102177363$$
$$x_{61} = 85.3466004225227$$
$$x_{26} = 87.4409955249159$$
$$x_{35} = 91.6297857297023$$
$$x_{37} = 93.7241808320955$$
$$x_{71} = 97.9129710368819$$
$$x_{29} = 100.007366139275$$
$$x_{6} = 110.479341651241$$
$$x_{10} = 112.573736753634$$
$$x_{46} = 791.15774992903$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} < x_{39}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{39} - \frac{1}{10}$$
=
$$-45867.7763411866 + - \frac{1}{10}$$
=
$$-45867.8763411866$$
lo sustituimos en la expresión
$$5 \sin{\left(x \right)} + \cos{\left(2 x \right)} > -2$$
$$5 \sin{\left(-45867.8763411866 \right)} + \cos{\left(\left(-45867.8763411866\right) 2 \right)} > -2$$
-2.60182118651354 > -2

Entonces
$$x < -45867.7763411866$$
no se cumple
significa que una de las soluciones de nuestra ecuación será con:
$$x > -45867.7763411866 \wedge x < -643.502895210309$$
         _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____  
        /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /
-------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-------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-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------
       x39      x15      x64      x67      x49      x44      x63      x27      x50      x48      x45      x43      x56      x38      x24      x32      x18      x12      x23      x8      x25      x11      x57      x17      x16      x30      x4      x65      x9      x7      x68      x20      x58      x22      x54      x52      x21      x62      x51      x53      x42      x14      x66      x28      x36      x70      x60      x40      x34      x13      x1      x55      x41      x33      x5      x69      x59      x47      x19      x2      x31      x3      x61      x26      x35      x37      x71      x29      x6      x10      x46

Recibiremos otras soluciones de la desigualdad pasando al polo siguiente etc.
etc.
Respuesta:
$$x > -45867.7763411866 \wedge x < -643.502895210309$$
$$x > -239.284640448423 \wedge x < -101.054563690472$$
$$x > -96.8657734856853 \wedge x < -94.7713783832921$$
$$x > -90.5825881785057 \wedge x < -88.4881930761125$$
$$x > -84.2994028713261 \wedge x < -82.2050077689329$$
$$x > -78.0162175641465 \wedge x < -75.9218224617533$$
$$x > -71.733032256967 \wedge x < -69.6386371545737$$
$$x > -65.4498469497874 \wedge x < -63.3554518473942$$
$$x > -59.1666616426078 \wedge x < -57.0722665402146$$
$$x > -52.8834763354282 \wedge x < -50.789081233035$$
$$x > -46.6002910282486 \wedge x < -44.5058959258554$$
$$x > -40.317105721069 \wedge x < -38.2227106186758$$
$$x > -34.0339204138894 \wedge x < -31.9395253114962$$
$$x > -27.7507351067098 \wedge x < -25.6563400043166$$
$$x > -21.4675497995303 \wedge x < -19.3731546971371$$
$$x > -15.1843644923507 \wedge x < -13.0899693899575$$
$$x > -8.90117918517108 \wedge x < -6.80678408277789$$
$$x > -2.61799387799149 \wedge x < -0.523598775598299$$
$$x > 3.66519142918809 \wedge x < 5.75958653158129$$
$$x > 9.94837673636768 \wedge x < 12.0427718387609$$
$$x > 16.2315620435473 \wedge x < 18.3259571459405$$
$$x > 22.5147473507269 \wedge x < 24.60914245312$$
$$x > 28.7979326579064 \wedge x < 30.8923277602996$$
$$x > 35.081117965086 \wedge x < 37.1755130674792$$
$$x > 41.3643032722656 \wedge x < 43.4586983746588$$
$$x > 47.6474885794452 \wedge x < 49.7418836818384$$
$$x > 53.9306738866248 \wedge x < 56.025068989018$$
$$x > 60.2138591938044 \wedge x < 62.3082542961976$$
$$x > 66.497044500984 \wedge x < 68.5914396033772$$
$$x > 72.7802298081635 \wedge x < 74.8746249105567$$
$$x > 79.0634151153431 \wedge x < 81.1578102177363$$
$$x > 85.3466004225227 \wedge x < 87.4409955249159$$
$$x > 91.6297857297023 \wedge x < 93.7241808320955$$
$$x > 97.9129710368819 \wedge x < 100.007366139275$$
$$x > 110.479341651241 \wedge x < 112.573736753634$$
$$x > 791.15774992903$$
Solución de la desigualdad en el gráfico
Respuesta rápida 2 [src]
    7*pi     11*pi       
[0, ----) U (-----, 2*pi]
     6         6         
$$x\ in\ \left[0, \frac{7 \pi}{6}\right) \cup \left(\frac{11 \pi}{6}, 2 \pi\right]$$
x in Union(Interval.Ropen(0, 7*pi/6), Interval.Lopen(11*pi/6, 2*pi))
Respuesta rápida [src]
  /   /            7*pi\     /           11*pi    \\
Or|And|0 <= x, x < ----|, And|x <= 2*pi, ----- < x||
  \   \             6  /     \             6      //
$$\left(0 \leq x \wedge x < \frac{7 \pi}{6}\right) \vee \left(x \leq 2 \pi \wedge \frac{11 \pi}{6} < x\right)$$
((0 <= x)∧(x < 7*pi/6))∨((x <= 2*pi)∧(11*pi/6 < x))
Gráfico
cos2x+5sin>-2 desigualdades