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受欢迎的微积分 >

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

解答

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

解答

- ln x^{2} + 1 + C

求解步骤

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

提出常数:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= - 2 \cdot \int \frac{x}{x ^{2} + 1} d x

使用换元积分法

= - 2 \cdot \int \frac{1}{2 u} d u

提出常数:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= - 2 \cdot \frac{1}{2} \cdot \int \frac{1}{u} d u

使用积分常见定则:

\int \frac{1}{u} d u = ln (∣ u ∣)

= - 2 \cdot \frac{1}{2} ln ∣ u ∣

u = x^{2} + 1

代回

= - 2 \cdot \frac{1}{2} ln x^{2} + 1

化简

- 2 \cdot \frac{1}{2} ln x^{2} + 1 : - ln x^{2} + 1

= - ln x^{2} + 1

解答补常数

= - ln x^{2} + 1 + C

作图

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