What is the integral of (x+2)/(x^3+9x) ?

The integral of (x+2)/(x^3+9x) is 1/3 arctan(x/3)+2(1/9 ln|x|-1/18 ln|x^2+9|)+C

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integral of (x+2)/(x^3+9x)

\int \frac{x + 2}{x ^{3} + 9 x} d x

\frac{1}{3} arctan (\frac{x}{3}) + 2 (\frac{1}{9} ln ∣ x ∣ - \frac{1}{18} ln x^{2} + 9) + C

Solution steps

\int \frac{x + 2}{x ^{3} + 9 x} d x

Expand

\frac{x + 2}{x ^{3} + 9 x} : \frac{x}{x ^{3} + 9 x} + \frac{2}{x ^{3} + 9 x}

Apply the Sum Rule:

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

= \int \frac{x}{x ^{3} + 9 x} d x + \int \frac{2}{x ^{3} + 9 x} d x

\int \frac{x}{x ^{3} + 9 x} d x = \frac{1}{3} arctan (\frac{x}{3})

\int \frac{2}{x ^{3} + 9 x} d x = 2 (\frac{1}{9} ln ∣ x ∣ - \frac{1}{18} ln x^{2} + 9)

= \frac{1}{3} arctan (\frac{x}{3}) + 2 (\frac{1}{9} ln ∣ x ∣ - \frac{1}{18} ln x^{2} + 9)

Add a constant to the solution

= \frac{1}{3} arctan (\frac{x}{3}) + 2 (\frac{1}{9} ln ∣ x ∣ - \frac{1}{18} ln x^{2} + 9) + C

What is the integral of (x+2)/(x^3+9x) ?
The integral of (x+2)/(x^3+9x) is 1/3 arctan(x/3)+2(1/9 ln|x|-1/18 ln|x^2+9|)+C