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受欢迎的三角函数 >

sin^5(a)=16sin^5(a)-20sin^3(a)+5sin(a)

解答

sin^{5} (a) = 16 sin^{5} (a) - 20 sin^{3} (a) + 5 sin (a)

解答

a = 2 πn, a = π + 2 πn, a = - 0.61547 \dots + 2 πn, a = π + 0.61547 \dots + 2 πn, a = 0.61547 \dots + 2 πn, a = π - 0.61547 \dots + 2 πn, a = \frac{3 π}{2} + 2 πn, a = \frac{π}{2} + 2 πn

+1

度数

a = 0^{\circ} + 36 0^{\circ} n, a = 18 0^{\circ} + 36 0^{\circ} n, a = - 35.26438 \dots^{\circ} + 36 0^{\circ} n, a = 215.26438 \dots^{\circ} + 36 0^{\circ} n, a = 35.26438 \dots^{\circ} + 36 0^{\circ} n, a = 144.73561 \dots^{\circ} + 36 0^{\circ} n, a = 27 0^{\circ} + 36 0^{\circ} n, a = 9 0^{\circ} + 36 0^{\circ} n

求解步骤

sin^{5} (a) = 16 sin^{5} (a) - 20 sin^{3} (a) + 5 sin (a)

用替代法求解

sin^{5} (a) = 16 sin^{5} (a) - 20 sin^{3} (a) + 5 sin (a)

令

: sin (a) = u

u^{5} = 16 u^{5} - 20 u^{3} + 5 u

u^{5} = 16 u^{5} - 20 u^{3} + 5 u : u = 0, u = - \frac{3}{3}, u = \frac{3}{3}, u = - 1, u = 1

u^{5} = 16 u^{5} - 20 u^{3} + 5 u

交换两边

16 u^{5} - 20 u^{3} + 5 u = u^{5}

将

u^{5}

para o lado esquerdo

16 u^{5} - 20 u^{3} + 5 u = u^{5}

两边减去

u^{5}

16 u^{5} - 20 u^{3} + 5 u - u^{5} = u^{5} - u^{5}

化简

15 u^{5} - 20 u^{3} + 5 u = 0

15 u^{5} - 20 u^{3} + 5 u = 0

因式分解

15 u^{5} - 20 u^{3} + 5 u : 5 u (3 u + 1) (3 u - 1) (u + 1) (u - 1)

15 u^{5} - 20 u^{3} + 5 u

因式分解出通项

5 u : 5 u (3 u^{4} - 4 u^{2} + 1)

15 u^{5} - 20 u^{3} + 5 u

使用指数法则:

a^{b + c} = a^{b} a^{c}

u^{3} = u^{2} u

= 15 u^{4} u - 20 u^{2} u + 5 u

将

20

改写为

5 \cdot 4

将

15

改写为

5 \cdot 3

= 5 \cdot 3 u^{4} u - 5 \cdot 4 u^{2} u + 5 u

因式分解出通项

5 u

= 5 u (3 u^{4} - 4 u^{2} + 1)

= 5 u (3 u^{4} - 4 u^{2} + 1)

分解

3 u^{4} - 4 u^{2} + 1 : (3 u + 1) (3 u - 1) (u + 1) (u - 1)

3 u^{4} - 4 u^{2} + 1

令

u = u^{2}

= 3 u^{2} - 4 u + 1

分解

3 u^{2} - 4 u + 1 : (3 u - 1) (u - 1)

3 u^{2} - 4 u + 1

将表达式拆分成组

3 u^{2} - 4 u + 1

定义

3

的因数:

1, 3

3

约数 (因数)

找到

3

的质因数:

3

3

3

是质数，因此无法因数分解

= 3

加 1

1

3

的因数

1, 3

3

的负因数:

- 1, - 3

将因数乘以

- 1

得到负因数

- 1, - 3

对于每两个因数

u * v = 3

，检验是否

u + v = - 4

检验

u = 1, v = 3 : u * v = 3, u + v = 4 \Rightarrow

假检验

u = - 1, v = - 3 : u * v = 3, u + v = - 4 \Rightarrow

真

u = - 1, v = - 3

分组为

(a x^{2} + ux) + (vx + c)

(3 u^{2} - u) + (- 3 u + 1)

= (3 u^{2} - u) + (- 3 u + 1)

从

3 u^{2} - u

分解出因式

u

:

u (3 u - 1)

3 u^{2} - u

使用指数法则:

a^{b + c} = a^{b} a^{c}

u^{2} = uu

= 3 uu - u

因式分解出通项

u

= u (3 u - 1)

从

- 3 u + 1

分解出因式

- 1

:

- (3 u - 1)

- 3 u + 1

因式分解出通项

- 1

= - (3 u - 1)

= u (3 u - 1) - (3 u - 1)

因式分解出通项

3 u - 1

= (3 u - 1) (u - 1)

= (3 u - 1) (u - 1)

u = u^{2}

代回

= (u^{2} - 1) (3 u^{2} - 1)

分解

3 u^{2} - 1 : (3 u + 1) (3 u - 1)

3 u^{2} - 1

将

3 u^{2} - 1

改写为

(3 u)^{2} - 1^{2}

3 u^{2} - 1

使用根式运算法则:

a = (a)^{2}

3 = (3)^{2}

= (3)^{2} u^{2} - 1

将

1

改写为

1^{2}

= (3)^{2} u^{2} - 1^{2}

使用指数法则:

a^{m} b^{m} = (ab)^{m}

(3)^{2} u^{2} = (3 u)^{2}

= (3 u)^{2} - 1^{2}

= (3 u)^{2} - 1^{2}

使用平方差公式:

x^{2} - y^{2} = (x + y) (x - y)

(3 u)^{2} - 1^{2} = (3 u + 1) (3 u - 1)

= (3 u + 1) (3 u - 1)

= (3 u + 1) (3 u - 1) (u^{2} - 1)

分解

u^{2} - 1 : (u + 1) (u - 1)

u^{2} - 1

将

1

改写为

1^{2}

= u^{2} - 1^{2}

使用平方差公式:

x^{2} - y^{2} = (x + y) (x - y)

u^{2} - 1^{2} = (u + 1) (u - 1)

= (u + 1) (u - 1)

= (3 u + 1) (3 u - 1) (u + 1) (u - 1)

= 5 u (3 u + 1) (3 u - 1) (u + 1) (u - 1)

5 u (3 u + 1) (3 u - 1) (u + 1) (u - 1) = 0

使用零因数法则： If

ab = 0

then

a = 0

or

b = 0

u = 0 or 3 u + 1 = 0 or 3 u - 1 = 0 or u + 1 = 0 or u - 1 = 0

解

3 u + 1 = 0 : u = - \frac{3}{3}

3 u + 1 = 0

将

1

到右边

3 u + 1 = 0

两边减去

1

3 u + 1 - 1 = 0 - 1

化简

3 u = - 1

3 u = - 1

两边除以

3

3 u = - 1

两边除以

3

\frac{3 u}{3} = \frac{- 1}{3}

化简

\frac{3 u}{3} = \frac{- 1}{3}

化简

\frac{3 u}{3} : u

\frac{3 u}{3}

约分:

3

= u

化简

\frac{- 1}{3} : - \frac{3}{3}

\frac{- 1}{3}

使用分式法则:

\frac{- a}{b} = - \frac{a}{b}

= - \frac{1}{3}

- \frac{1}{3}

有理化:

- \frac{3}{3}

- \frac{1}{3}

乘以共轭根式

\frac{3}{3}

= - \frac{1 \cdot 3}{3 3}

1 \cdot 3 = 3

33 = 3

33

使用根式运算法则:

a a = a

33 = 3

= 3

= - \frac{3}{3}

= - \frac{3}{3}

u = - \frac{3}{3}

u = - \frac{3}{3}

u = - \frac{3}{3}

解

3 u - 1 = 0 : u = \frac{3}{3}

3 u - 1 = 0

将

1

到右边

3 u - 1 = 0

两边加上

1

3 u - 1 + 1 = 0 + 1

化简

3 u = 1

3 u = 1

两边除以

3

3 u = 1

两边除以

3

\frac{3 u}{3} = \frac{1}{3}

化简

\frac{3 u}{3} = \frac{1}{3}

化简

\frac{3 u}{3} : u

\frac{3 u}{3}

约分:

3

= u

化简

\frac{1}{3} : \frac{3}{3}

\frac{1}{3}

乘以共轭根式

\frac{3}{3}

= \frac{1 \cdot 3}{3 3}

1 \cdot 3 = 3

33 = 3

33

使用根式运算法则:

a a = a

33 = 3

= 3

= \frac{3}{3}

u = \frac{3}{3}

u = \frac{3}{3}

u = \frac{3}{3}

解

u + 1 = 0 : u = - 1

u + 1 = 0

将

1

到右边

u + 1 = 0

两边减去

1

u + 1 - 1 = 0 - 1

化简

u = - 1

u = - 1

解

u - 1 = 0 : u = 1

u - 1 = 0

将

1

到右边

u - 1 = 0

两边加上

1

u - 1 + 1 = 0 + 1

化简

u = 1

u = 1

解为

u = 0, u = - \frac{3}{3}, u = \frac{3}{3}, u = - 1, u = 1

u = sin (a)

代回

sin (a) = 0, sin (a) = - \frac{3}{3}, sin (a) = \frac{3}{3}, sin (a) = - 1, sin (a) = 1

sin (a) = 0, sin (a) = - \frac{3}{3}, sin (a) = \frac{3}{3}, sin (a) = - 1, sin (a) = 1

sin (a) = 0 : a = 2 πn, a = π + 2 πn

sin (a) = 0

sin (a) = 0

的通解

sin (x)

周期表（周期为

2 πn

"）：

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}

a = 0 + 2 πn, a = π + 2 πn

a = 0 + 2 πn, a = π + 2 πn

解

a = 0 + 2 πn : a = 2 πn

a = 0 + 2 πn

0 + 2 πn = 2 πn

a = 2 πn

a = 2 πn, a = π + 2 πn

sin (a) = - \frac{3}{3} : a = arcsin (- \frac{3}{3}) + 2 πn, a = π + arcsin (\frac{3}{3}) + 2 πn

sin (a) = - \frac{3}{3}

使用反三角函数性质

sin (a) = - \frac{3}{3}

sin (a) = - \frac{3}{3}

的通解

sin (x) = - a \Rightarrow x = arcsin (- a) + 2 πn, x = π + arcsin (a) + 2 πn

a = arcsin (- \frac{3}{3}) + 2 πn, a = π + arcsin (\frac{3}{3}) + 2 πn

a = arcsin (- \frac{3}{3}) + 2 πn, a = π + arcsin (\frac{3}{3}) + 2 πn

sin (a) = \frac{3}{3} : a = arcsin (\frac{3}{3}) + 2 πn, a = π - arcsin (\frac{3}{3}) + 2 πn

sin (a) = \frac{3}{3}

使用反三角函数性质

sin (a) = \frac{3}{3}

sin (a) = \frac{3}{3}

的通解

sin (x) = a \Rightarrow x = arcsin (a) + 2 πn, x = π - arcsin (a) + 2 πn

a = arcsin (\frac{3}{3}) + 2 πn, a = π - arcsin (\frac{3}{3}) + 2 πn

a = arcsin (\frac{3}{3}) + 2 πn, a = π - arcsin (\frac{3}{3}) + 2 πn

sin (a) = - 1 : a = \frac{3 π}{2} + 2 πn

sin (a) = - 1

sin (a) = - 1

的通解

sin (x)

周期表（周期为

2 πn

"）：

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}

a = \frac{3 π}{2} + 2 πn

a = \frac{3 π}{2} + 2 πn

sin (a) = 1 : a = \frac{π}{2} + 2 πn

sin (a) = 1

sin (a) = 1

的通解

sin (x)

周期表（周期为

2 πn

"）：

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}

a = \frac{π}{2} + 2 πn

a = \frac{π}{2} + 2 πn

合并所有解

a = 2 πn, a = π + 2 πn, a = arcsin (- \frac{3}{3}) + 2 πn, a = π + arcsin (\frac{3}{3}) + 2 πn, a = arcsin (\frac{3}{3}) + 2 πn, a = π - arcsin (\frac{3}{3}) + 2 πn, a = \frac{3 π}{2} + 2 πn, a = \frac{π}{2} + 2 πn

以小数形式表示解

a = 2 πn, a = π + 2 πn, a = - 0.61547 \dots + 2 πn, a = π + 0.61547 \dots + 2 πn, a = 0.61547 \dots + 2 πn, a = π - 0.61547 \dots + 2 πn, a = \frac{3 π}{2} + 2 πn, a = \frac{π}{2} + 2 πn

作图

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