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受欢迎的三角函数 >

cos^2(x)=-4

解答

cos^{2} (x) = - 4

解答

x \in R 无解

求解步骤

cos^{2} (x) = - 4

用替代法求解

cos^{2} (x) = - 4

令

: cos (x) = u

u^{2} = - 4

u^{2} = - 4 : u = 2 i, u = - 2 i

u^{2} = - 4

对于

x^{2} = f (a)

解为

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

u = - 4, u = - - 4

化简

- 4 : 2 i

- 4

使用根式运算法则:

- a = - 1 a

- 4 = - 1 4

= - 1 4

使用虚数运算法则:

- 1 = i

= 4 i

4 = 2

4

因式分解数字:

4 = 2^{2}

= 2^{2}

使用根式运算法则:

n a^{n} = a

2^{2} = 2

= 2

= 2 i

化简

- - 4 : - 2 i

- - 4

化简

- 4 : 2 i

- 4

使用根式运算法则:

- a = - 1 a

- 4 = - 1 4

= - 1 4

使用虚数运算法则:

- 1 = i

= 4 i

4 = 2

4

因式分解数字:

4 = 2^{2}

= 2^{2}

使用根式运算法则:

n a^{n} = a

2^{2} = 2

= 2

= 2 i

= - 2 i

u = 2 i, u = - 2 i

u = cos (x)

代回

cos (x) = 2 i, cos (x) = - 2 i

cos (x) = 2 i, cos (x) = - 2 i

cos (x) = 2 i :

无解

cos (x) = 2 i

无解

cos (x) = - 2 i :

无解

cos (x) = - 2 i

无解

合并所有解

x \in R 无解

作图

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