What is the integral of 1/(x^2+6x+18) ?

The integral of 1/(x^2+6x+18) is 1/3 arctan((x+3)/3)+C

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integral of 1/(x^2+6x+18)

\int \frac{1}{x ^{2} + 6 x + 18} d x

\frac{1}{3} arctan (\frac{x + 3}{3}) + C

Solution steps

\int \frac{1}{x ^{2} + 6 x + 18} d x

Complete the square

x^{2} + 6 x + 18 : (x + 3)^{2} + 9

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

Apply u-substitution

= \int \frac{1}{u ^{2} + 9} d u

Apply Integral Substitution

= \int \frac{1}{3 ( v ^{2} + 1 )} d v

Take the constant out:

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

= \frac{1}{3} \cdot \int \frac{1}{v ^{2} + 1} d v

Use the common integral:

\int \frac{1}{v ^{2} + 1} d v = arctan (v)

= \frac{1}{3} arctan (v)

Substitute back

= \frac{1}{3} arctan (\frac{x + 3}{3})

Add a constant to the solution

= \frac{1}{3} arctan (\frac{x + 3}{3}) + C

What is the integral of 1/(x^2+6x+18) ?
The integral of 1/(x^2+6x+18) is 1/3 arctan((x+3)/3)+C