What is the integral of 1/(x(x^2+a)) ?

The integral of 1/(x(x^2+a)) is 1/(2a)(-ln((|x^2+a|}{|a|})+ln|\frac{x^2+a)/a-1|)+C

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

\int \frac{1}{x ( x ^{2} + a )} d x

\frac{1}{2 a} (- ln (\frac{x ^{2} + a}{∣ a ∣}) + ln \frac{x ^{2} + a}{a} - 1) + C

Solution steps

\int \frac{1}{x ( x ^{2} + a )} d x

Apply u-substitution

= \int \frac{1}{2 u ( u + a )} d u

Take the constant out:

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

= \frac{1}{2} \cdot \int \frac{1}{u ( u + a )} d u

Apply u-substitution

= \frac{1}{2} \cdot \int \frac{1}{( v - a ) v} d v

v - a = a (\frac{v}{a} - 1)

= \frac{1}{2} \cdot \int \frac{1}{a ( \frac{v}{a} - 1 ) v} d v

Take the constant out:

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

= \frac{1}{2} \cdot \frac{1}{a} \cdot \int \frac{1}{( \frac{v}{a} - 1 ) v} d v

Apply u-substitution

= \frac{1}{2} \cdot \frac{1}{a} \cdot \int \frac{1}{w ( w - 1 )} d w

Take the partial fraction of

\frac{1}{w ( w - 1 )} : - \frac{1}{w} + \frac{1}{w - 1}

= \frac{1}{2} \cdot \frac{1}{a} \cdot \int - \frac{1}{w} + \frac{1}{w - 1} d w

Apply the Sum Rule:

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

= \frac{1}{2} \cdot \frac{1}{a} (- \int \frac{1}{w} d w + \int \frac{1}{w - 1} d w)

\int \frac{1}{w} d w = ln ∣ w ∣

\int \frac{1}{w - 1} d w = ln ∣ w - 1 ∣

= \frac{1}{2} \cdot \frac{1}{a} (- ln ∣ w ∣ + ln ∣ w - 1 ∣)

Substitute back

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

Simplify

\frac{1}{2} \cdot \frac{1}{a} (- ln \frac{x ^{2} + a}{a} + ln \frac{x ^{2} + a}{a} - 1) : \frac{1}{2 a} (- ln (\frac{x ^{2} + a}{∣ a ∣}) + ln \frac{x ^{2} + a}{a} - 1)

= \frac{1}{2 a} (- ln (\frac{x ^{2} + a}{∣ a ∣}) + ln \frac{x ^{2} + a}{a} - 1)

Add a constant to the solution

= \frac{1}{2 a} (- ln (\frac{x ^{2} + a}{∣ a ∣}) + ln \frac{x ^{2} + a}{a} - 1) + C

What is the integral of 1/(x(x^2+a)) ?
The integral of 1/(x(x^2+a)) is 1/(2a)(-ln((|x^2+a|}{|a|})+ln|\frac{x^2+a)/a-1|)+C