limit as x approaches 4-of (2-x)/(x-4)

解

x \to 4 - lim (\frac{2 - x}{x - 4})

\infty

解答ステップ

x \to 4 - lim (\frac{2 - x}{x - 4})

\frac{2 - x}{x - 4} = (2 - x) \frac{1}{x - 4}

= x \to 4 - lim ((2 - x) \frac{1}{x - 4})

x \to a lim [f (x) \cdot g (x)] = x \to a lim f (x) \cdot x \to a lim g (x)

不定形式の場合を除く

= x \to 4 - lim (2 - x) \cdot x \to 4 - lim (\frac{1}{x - 4})

x \to 4 - lim (2 - x) = - 2

x \to 4 - lim (\frac{1}{x - 4}) = - \infty

= (- 2) (- \infty)

無限大の特性を適用する:

- c \cdot (- \infty) = \infty

= \infty