What is the integral of 1/(x^2+12x+85) ?

The integral of 1/(x^2+12x+85) is 1/7 arctan((x+6)/7)+C

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integral of 1/(x^2+12x+85)

\int \frac{1}{x ^{2} + 12 x + 85} d x

\frac{1}{7} arctan (\frac{x + 6}{7}) + C

Solution steps

\int \frac{1}{x ^{2} + 12 x + 85} d x

Complete the square

x^{2} + 12 x + 85 : (x + 6)^{2} + 49

= \int \frac{1}{( x + 6 ) ^{2} + 49} d x

Apply u-substitution

= \int \frac{1}{u ^{2} + 49} d u

Apply Integral Substitution

= \int \frac{1}{7 ( 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}{7} \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}{7} arctan (v)

Substitute back

= \frac{1}{7} arctan (\frac{x + 6}{7})

Add a constant to the solution

= \frac{1}{7} arctan (\frac{x + 6}{7}) + C

What is the integral of 1/(x^2+12x+85) ?
The integral of 1/(x^2+12x+85) is 1/7 arctan((x+6)/7)+C