What is the integral from 0 to 2 of (1/(x^2+x+1)) ?

The integral from 0 to 2 of (1/(x^2+x+1)) is (6arctan(5/(sqrt(3)))-pi)/(3sqrt(3))

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integral from 0 to 2 of (1/(x^2+x+1))

\int_{0}^{2} (\frac{1}{x ^{2} + x + 1}) d x

\frac{6 arctan ( \frac{5}{3} ) - π}{3 3}

Decimal

0.82413 \dots

Solution steps

\int_{0}^{2} \frac{1}{x ^{2} + x + 1} d x

Complete the square

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

= \int_{0}^{2} \frac{1}{( x + \frac{1}{2} ) ^{2} + \frac{3}{4}} d x

Apply u-substitution

= \int_{\frac{1}{2}}^{\frac{5}{2}} \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}{2}}^{\frac{5}{2}} \frac{1}{4 u ^{2} + 3} d u

Apply Integral Substitution

= 4 \cdot \int_{\frac{1}{3}}^{\frac{5}{3}} \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}{3}}^{\frac{5}{3}} \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)]_{\frac{1}{3}}^{\frac{5}{3}}

Simplify

4 \cdot \frac{1}{2 3} [arctan (v)]_{\frac{1}{3}}^{\frac{5}{3}} : \frac{2}{3} [arctan (v)]_{\frac{1}{3}}^{\frac{5}{3}}

= \frac{2}{3} [arctan (v)]_{\frac{1}{3}}^{\frac{5}{3}}

Compute the boundaries:

arctan (\frac{5}{3}) - \frac{π}{6}

= \frac{2}{3} (arctan (\frac{5}{3}) - \frac{π}{6})

Simplify

= \frac{6 arctan ( \frac{5}{3} ) - π}{3 3}

What is the integral from 0 to 2 of (1/(x^2+x+1)) ?
The integral from 0 to 2 of (1/(x^2+x+1)) is (6arctan(5/(sqrt(3)))-pi)/(3sqrt(3))