What is the integral of (2x-3)/(x^2+4x+20) ?

The integral of (2x-3)/(x^2+4x+20) is ln| 1/16 (x+2)^2+1|-7/4 arctan(1/4 (x+2))+C

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integral of (2x-3)/(x^2+4x+20)

\int \frac{2 x - 3}{x ^{2} + 4 x + 20} d x

ln \frac{1}{16} (x + 2)^{2} + 1 - \frac{7}{4} arctan (\frac{1}{4} (x + 2)) + C

Solution steps

\int \frac{2 x - 3}{x ^{2} + 4 x + 20} d x

Complete the square

x^{2} + 4 x + 20 : (x + 2)^{2} + 16

= \int \frac{2 x - 3}{( x + 2 ) ^{2} + 16} d x

Apply u-substitution

: \int \frac{2 u - 7}{u ^{2} + 16} d u

= \int \frac{2 u - 7}{u ^{2} + 16} d u

Apply Integral Substitution

= \int \frac{8 v - 7}{4 ( 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}{4} \cdot \int \frac{8 v - 7}{v ^{2} + 1} d v

Expand

\frac{8 v - 7}{v ^{2} + 1} : \frac{8 v}{v ^{2} + 1} - \frac{7}{v ^{2} + 1}

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}{4} (\int \frac{8 v}{v ^{2} + 1} d v - \int \frac{7}{v ^{2} + 1} d v)

\int \frac{8 v}{v ^{2} + 1} d v = 4 ln v^{2} + 1

\int \frac{7}{v ^{2} + 1} d v = 7 arctan (v)

= \frac{1}{4} (4 ln v^{2} + 1 - 7 arctan (v))

Substitute back

= \frac{1}{4} (4 ln (\frac{x + 2}{4})^{2} + 1 - 7 arctan (\frac{x + 2}{4}))

Simplify

\frac{1}{4} (4 ln (\frac{x + 2}{4})^{2} + 1 - 7 arctan (\frac{x + 2}{4})) : ln \frac{1}{16} (x + 2)^{2} + 1 - \frac{7}{4} arctan (\frac{1}{4} (x + 2))

= ln \frac{1}{16} (x + 2)^{2} + 1 - \frac{7}{4} arctan (\frac{1}{4} (x + 2))

Add a constant to the solution

= ln \frac{1}{16} (x + 2)^{2} + 1 - \frac{7}{4} arctan (\frac{1}{4} (x + 2)) + C

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What is the integral of (2x-3)/(x^2+4x+20) ?
The integral of (2x-3)/(x^2+4x+20) is ln| 1/16 (x+2)^2+1|-7/4 arctan(1/4 (x+2))+C