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Popular >

2sin^2(x)-4cos^2(x)+1=0

Solución

2 sin^{2} (x) - 4 cos^{2} (x) + 1 = 0

Solución

x = \frac{π}{4} + 2 πn, x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

Grados

x = 4 5^{\circ} + 36 0^{\circ} n, x = 13 5^{\circ} + 36 0^{\circ} n, x = 22 5^{\circ} + 36 0^{\circ} n, x = 31 5^{\circ} + 36 0^{\circ} n

Pasos de solución

2 sin^{2} (x) - 4 cos^{2} (x) + 1 = 0

Re-escribir usando identidades trigonométricas

1 + 2 sin^{2} (x) - 4 cos^{2} (x)

Utilizar la identidad pitagórica:

cos^{2} (x) + sin^{2} (x) = 1

cos^{2} (x) = 1 - sin^{2} (x)

= 1 + 2 sin^{2} (x) - 4 (1 - sin^{2} (x))

Simplificar

1 + 2 sin^{2} (x) - 4 (1 - sin^{2} (x)) : 6 sin^{2} (x) - 3

1 + 2 sin^{2} (x) - 4 (1 - sin^{2} (x))

Expandir

- 4 (1 - sin^{2} (x)) : - 4 + 4 sin^{2} (x)

- 4 (1 - sin^{2} (x))

Poner los parentesis utilizando:

a (b - c) = ab - a c

a = - 4, b = 1, c = sin^{2} (x)

= - 4 \cdot 1 - (- 4) sin^{2} (x)

Aplicar las reglas de los signos

- (- a) = a

= - 4 \cdot 1 + 4 sin^{2} (x)

Multiplicar los numeros:

4 \cdot 1 = 4

= - 4 + 4 sin^{2} (x)

= 1 + 2 sin^{2} (x) - 4 + 4 sin^{2} (x)

Simplificar

1 + 2 sin^{2} (x) - 4 + 4 sin^{2} (x) : 6 sin^{2} (x) - 3

1 + 2 sin^{2} (x) - 4 + 4 sin^{2} (x)

Agrupar términos semejantes

= 2 sin^{2} (x) + 4 sin^{2} (x) + 1 - 4

Sumar elementos similares:

2 sin^{2} (x) + 4 sin^{2} (x) = 6 sin^{2} (x)

= 6 sin^{2} (x) + 1 - 4

Sumar/restar lo siguiente:

1 - 4 = - 3

= 6 sin^{2} (x) - 3

= 6 sin^{2} (x) - 3

= 6 sin^{2} (x) - 3

- 3 + 6 sin^{2} (x) = 0

Usando el método de sustitución

- 3 + 6 sin^{2} (x) = 0

Sea:

sin (x) = u

- 3 + 6 u^{2} = 0

- 3 + 6 u^{2} = 0 : u = \frac{1}{2}, u = - \frac{1}{2}

- 3 + 6 u^{2} = 0

Mover

3

al lado derecho

- 3 + 6 u^{2} = 0

Sumar

3

a ambos lados

- 3 + 6 u^{2} + 3 = 0 + 3

Simplificar

6 u^{2} = 3

6 u^{2} = 3

Dividir ambos lados entre

6

6 u^{2} = 3

Dividir ambos lados entre

6

\frac{6 u ^{2}}{6} = \frac{3}{6}

Simplificar

u^{2} = \frac{1}{2}

u^{2} = \frac{1}{2}

Para

x^{2} = f (a)

las soluciones son

x = f (a), - f (a)

u = \frac{1}{2}, u = - \frac{1}{2}

Sustituir en la ecuación

u = sin (x)

sin (x) = \frac{1}{2}, sin (x) = - \frac{1}{2}

sin (x) = \frac{1}{2}, sin (x) = - \frac{1}{2}

sin (x) = \frac{1}{2} : x = \frac{π}{4} + 2 πn, x = \frac{3 π}{4} + 2 πn

sin (x) = \frac{1}{2}

Soluciones generales para

sin (x) = \frac{1}{2}

tabla de valores periódicos con

2 πn

intervalos:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

x = \frac{π}{4} + 2 πn, x = \frac{3 π}{4} + 2 πn

x = \frac{π}{4} + 2 πn, x = \frac{3 π}{4} + 2 πn

sin (x) = - \frac{1}{2} : x = \frac{5 π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

sin (x) = - \frac{1}{2}

Soluciones generales para

sin (x) = - \frac{1}{2}

tabla de valores periódicos con

2 πn

intervalos:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

x = \frac{5 π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

x = \frac{5 π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

Combinar toda las soluciones

x = \frac{π}{4} + 2 πn, x = \frac{3 π}{4} + 2 πn, x = \frac{5 π}{4} + 2 πn, x = \frac{7 π}{4} + 2 πn

Ejemplos populares

solvefor x,-y^2-cos(x)=0 resolver para

x, - y^{2} - cos (x) = 0

cos(θ)= 6/16

cos (θ) = \frac{6}{16}

|cos(x)|=-1

∣ cos (x) ∣ = - 1

(sin(25)}{5.41}=\frac{sin(x))/9

\frac{sin ( 2 5 ^{\circ} )}{5.41} = \frac{sin ( x )}{9}

cos(θ)= 4/(sqrt(17))

cos (θ) = \frac{4}{17}