(x)=(x-1)/(x^2-3x-40)

解答

(x) = \frac{x - 1}{x ^{2} - 3 x - 40}

x \approx 0.02434 \dots, x \approx - 5.09138 \dots, x \approx 8.06704 \dots

求解步骤

(x) = \frac{x - 1}{x ^{2} - 3 x - 40}

在两边乘以

x^{2} - 3 x - 40

x (x^{2} - 3 x - 40) = x - 1

解

x (x^{2} - 3 x - 40) = x - 1 : x \approx 0.02434 \dots, x \approx - 5.09138 \dots, x \approx 8.06704 \dots

x \approx 0.02434 \dots, x \approx - 5.09138 \dots, x \approx 8.06704 \dots

验证解

找到无定义的点（奇点）:

x = 8, x = - 5

将不在定义域的点与解相综合:

x \approx 0.02434 \dots, x \approx - 5.09138 \dots, x \approx 8.06704 \dots

\frac{- 2 - \frac{14}{13}}{x + 2} = 1

7 = (\frac{10}{( 2 x + 3 )}) + 5

(\frac{2.4}{x + 17}) = 0.025

\frac{5}{1 - 3 x} = 3

\frac{15}{x + 7} = \frac{45}{x + 21}