定义域 ((x/(x+5)))/((x/(x+5))+5)

解答

定义域

\frac{( \frac{x}{x + 5} )}{( \frac{x}{x + 5} ) + 5}

x < - 5 or - 5 < x < - \frac{25}{6} or x > - \frac{25}{6}

间隔符号

(- \infty, - 5) \cup (- 5, - \frac{25}{6}) \cup (- \frac{25}{6}, \infty)

求解步骤

找到无定义的点（奇点）:

x = - \frac{25}{6}, x = - 5

函数定义域

x < - 5 or - 5 < x < - \frac{25}{6} or x > - \frac{25}{6}

d o main f (x) = \frac{1}{2 x}

d o main f (x) = 2 x^{3} - 6 x^{2}

d o main f (x) = - x + 7, - 3 \leq x \leq 9

d o main y = 15 - 3 x

d o main f (x) = \frac{x ^{2} - 25}{x ^{2} - 11 x + 18}