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

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

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

integral

\frac{1}{( x ^{2} + x + 1 )}

\frac{2}{3} arctan (\frac{2 x + 1}{3}) + C

Solution steps

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

Complete the square

x^{2} + x + 1 : (x + \frac{1}{2})^{2} + \frac{3}{4}

= \int \frac{1}{( x + \frac{1}{2} ) ^{2} + \frac{3}{4}} d x

Apply u-substitution

= \int \frac{4}{4 u ^{2} + 3} d u

Take the constant out:

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

= 4 \cdot \int \frac{1}{4 u ^{2} + 3} d u

Apply Integral Substitution

= 4 \cdot \int \frac{1}{2 3 ( v ^{2} + 1 )} d v

Take the constant out:

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

= 4 \cdot \frac{1}{2 3} \cdot \int \frac{1}{v ^{2} + 1} d v

Use the common integral:

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

= 4 \cdot \frac{1}{2 3} arctan (v)

Substitute back

= 4 \cdot \frac{1}{2 3} arctan (\frac{2}{3} (x + \frac{1}{2}))

Simplify

4 \cdot \frac{1}{2 3} arctan (\frac{2}{3} (x + \frac{1}{2})) : \frac{2}{3} arctan (\frac{2 x + 1}{3})

= \frac{2}{3} arctan (\frac{2 x + 1}{3})

Add a constant to the solution

= \frac{2}{3} arctan (\frac{2 x + 1}{3}) + C

in t e g r a l cos^{3} (x) - cos (x)

in t e g r a l sin (2 - 4 x)

in t e g r a l \frac{x}{( x ^{2} + a ^{2} )}

in t e g r a l \frac{1}{( x - 1 )}

in t e g r a l x^{3} (e^{x})^{2}

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