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受欢迎的三角函数 >

(tan(x)(-tan^2(x)+3))/(1-tan^2(x))=0

解答

\frac{tan ( x ) ( - tan ^{2} ( x ) + 3 )}{1 - tan ^{2} ( x )} = 0

解答

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

+1

度数

x = 0^{\circ} + 18 0^{\circ} n, x = 12 0^{\circ} + 18 0^{\circ} n, x = 6 0^{\circ} + 18 0^{\circ} n

求解步骤

\frac{tan ( x ) ( - tan ^{2} ( x ) + 3 )}{1 - tan ^{2} ( x )} = 0

用替代法求解

\frac{tan ( x ) ( - tan ^{2} ( x ) + 3 )}{1 - tan ^{2} ( x )} = 0

令

: tan (x) = u

\frac{u ( - u ^{2} + 3 )}{1 - u ^{2}} = 0

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

\frac{u ( - u ^{2} + 3 )}{1 - u ^{2}} = 0

\frac{f ( x )}{g ( x )} = 0 \Rightarrow f (x) = 0

u (- u^{2} + 3) = 0

解

u (- u^{2} + 3) = 0 : u = 0, u = - 3, u = 3

u (- u^{2} + 3) = 0

因式分解

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

u (- u^{2} + 3)

分解

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

- u^{2} + 3

因式分解出通项

- 1

= - (u^{2} - 3)

分解

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

u^{2} - 3

使用根式运算法则:

a = (a)^{2}

3 = (3)^{2}

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

使用平方差公式:

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

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

= (u + 3) (u - 3)

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

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

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

使用零因数法则： If

ab = 0

then

a = 0

or

b = 0

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

解

u + 3 = 0 : u = - 3

u + 3 = 0

将

3

到右边

u + 3 = 0

两边减去

3

u + 3 - 3 = 0 - 3

化简

u = - 3

u = - 3

解

u - 3 = 0 : u = 3

u - 3 = 0

将

3

到右边

u - 3 = 0

两边加上

3

u - 3 + 3 = 0 + 3

化简

u = 3

u = 3

解为

u = 0, u = - 3, u = 3

u = 0, u = - 3, u = 3

验证解

找到无定义的点（奇点）:

u = 1, u = - 1

取

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

的分母，令其等于零

解

1 - u^{2} = 0 : u = 1, u = - 1

1 - u^{2} = 0

将

1

到右边

1 - u^{2} = 0

两边减去

1

1 - u^{2} - 1 = 0 - 1

化简

- u^{2} = - 1

- u^{2} = - 1

两边除以

- 1

- u^{2} = - 1

两边除以

- 1

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

化简

u^{2} = 1

u^{2} = 1

对于

x^{2} = f (a)

解为

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

u = 1, u = - 1

1 = 1

1

使用根式运算法则:

1 = 1

= 1

- 1 = - 1

- 1

使用根式运算法则:

1 = 1

1 = 1

= - 1

u = 1, u = - 1

以下点无定义

u = 1, u = - 1

将不在定义域的点与解相综合:

u = 0, u = - 3, u = 3

u = tan (x)

代回

tan (x) = 0, tan (x) = - 3, tan (x) = 3

tan (x) = 0, tan (x) = - 3, tan (x) = 3

tan (x) = 0 : x = πn

tan (x) = 0

tan (x) = 0

的通解

tan (x)

周期表（周期为

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} tan (x) 0 \frac{3}{3} 13 \pm \infty - 3 - 1 - \frac{3}{3}

x = 0 + πn

x = 0 + πn

解

x = 0 + πn : x = πn

x = 0 + πn

0 + πn = πn

x = πn

x = πn

tan (x) = - 3 : x = \frac{2 π}{3} + πn

tan (x) = - 3

tan (x) = - 3

的通解

tan (x)

周期表（周期为

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} tan (x) 0 \frac{3}{3} 13 \pm \infty - 3 - 1 - \frac{3}{3}

x = \frac{2 π}{3} + πn

x = \frac{2 π}{3} + πn

tan (x) = 3 : x = \frac{π}{3} + πn

tan (x) = 3

tan (x) = 3

的通解

tan (x)

周期表（周期为

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} tan (x) 0 \frac{3}{3} 13 \pm \infty - 3 - 1 - \frac{3}{3}

x = \frac{π}{3} + πn

x = \frac{π}{3} + πn

合并所有解

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

作图

流行的例子

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