integral of (x-5)/(x^2+4)

解答

\int \frac{x - 5}{x ^{2} + 4} d x

\frac{1}{2} ln x^{2} + 4 - \frac{5}{2} arctan (\frac{x}{2}) + C

求解步骤

\int \frac{x - 5}{x ^{2} + 4} d x

乘开

\frac{x - 5}{x ^{2} + 4} : \frac{x}{x ^{2} + 4} - \frac{5}{x ^{2} + 4}

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 \frac{x}{x ^{2} + 4} d x - \int \frac{5}{x ^{2} + 4} d x

\int \frac{x}{x ^{2} + 4} d x = \frac{1}{2} ln x^{2} + 4

\int \frac{5}{x ^{2} + 4} d x = \frac{5}{2} arctan (\frac{x}{2})

= \frac{1}{2} ln x^{2} + 4 - \frac{5}{2} arctan (\frac{x}{2})

解答补常数

= \frac{1}{2} ln x^{2} + 4 - \frac{5}{2} arctan (\frac{x}{2}) + C

\int sin^{3} (\frac{x}{a}) cos^{3} (\frac{x}{a}) d x

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