integral of (2x+5)/(x-1)

解答

\int \frac{2 x + 5}{x - 1} d x

2 (x - 1) + 7 ln ∣ x - 1 ∣ + C

求解步骤

\int \frac{2 x + 5}{x - 1} d x

使用换元积分法

= \int \frac{2 u + 7}{u} d u

乘开

\frac{2 u + 7}{u} : 2 + \frac{7}{u}

= \int 2 + \frac{7}{u} d u

使用积分加法定则:

\int f (x) \pm g (x) d x = \int f (x) d x \pm \int g (x) d x

= \int 2 d u + \int \frac{7}{u} d u

\int 2 d u = 2 u

\int \frac{7}{u} d u = 7 ln ∣ u ∣

= 2 u + 7 ln ∣ u ∣

u = x - 1

代回

= 2 (x - 1) + 7 ln ∣ x - 1 ∣

解答补常数

= 2 (x - 1) + 7 ln ∣ x - 1 ∣ + C

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