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

Lösung

\int (x + 1) x^{2} + x + 1 d x

\frac{1}{48} (16 (x^{2} + x + 1)^{\frac{3}{2}} + 3 (4 (x + \frac{1}{2}) x^{2} + x + 1 + 3 (ln 2 x + 1 + 3 \frac{4 x ^{2} + 4 x + 4}{3} - \frac{ln ( 3 )}{2}))) + C

Schritte zur Lösung

\int (x + 1) x^{2} + x + 1 d x

Vervollständige das Quadrat

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

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

Wende U-Substitution an

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

Entferne die Konstante:

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

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

Multipliziere aus

(2 u + 1) 4 u^{2} + 3 : 2 u 4 u^{2} + 3 + 4 u^{2} + 3

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

Wende die Summenregel an:

\int f (x) \pm g (x) d x = \int f (x) d x \pm \int g (x) d x

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

\int 2 u 4 u^{2} + 3 d u = \frac{1}{6} (4 u^{2} + 3)^{\frac{3}{2}}

\int 4 u^{2} + 3 d u = \frac{1}{4} (2 u 4 u^{2} + 3 + 3 (ln 2 u + 3 \frac{4 u ^{2} + 3}{3} - \frac{ln ( 3 )}{2}))

= \frac{1}{4} (\frac{1}{6} (4 u^{2} + 3)^{\frac{3}{2}} + \frac{1}{4} (2 u 4 u^{2} + 3 + 3 (ln 2 u + 3 \frac{4 u ^{2} + 3}{3} - \frac{ln ( 3 )}{2})))

Setze in

u = x + \frac{1}{2}

ein

= \frac{1}{4} \frac{1}{6} (4 (x + \frac{1}{2})^{2} + 3)^{\frac{3}{2}} + \frac{1}{4} 2 (x + \frac{1}{2}) 4 (x + \frac{1}{2})^{2} + 3 + 3 ln 2 (x + \frac{1}{2}) + 3 \frac{4 ( x + \frac{1}{2} ) ^{2} + 3}{3} - \frac{ln ( 3 )}{2}

Vereinfache

\frac{1}{4} \frac{1}{6} (4 (x + \frac{1}{2})^{2} + 3)^{\frac{3}{2}} + \frac{1}{4} 2 (x + \frac{1}{2}) 4 (x + \frac{1}{2})^{2} + 3 + 3 ln 2 (x + \frac{1}{2}) + 3 \frac{4 ( x + \frac{1}{2} ) ^{2} + 3}{3} - \frac{ln ( 3 )}{2} : \frac{1}{48} (16 (x^{2} + x + 1)^{\frac{3}{2}} + 3 (4 (x + \frac{1}{2}) x^{2} + x + 1 + 3 (ln 2 x + 1 + 3 \frac{4 x ^{2} + 4 x + 4}{3} - \frac{ln ( 3 )}{2})))

= \frac{1}{48} (16 (x^{2} + x + 1)^{\frac{3}{2}} + 3 (4 (x + \frac{1}{2}) x^{2} + x + 1 + 3 (ln 2 x + 1 + 3 \frac{4 x ^{2} + 4 x + 4}{3} - \frac{ln ( 3 )}{2})))

Füge eine Konstante zur Lösung hinzu

= \frac{1}{48} (16 (x^{2} + x + 1)^{\frac{3}{2}} + 3 (4 (x + \frac{1}{2}) x^{2} + x + 1 + 3 (ln 2 x + 1 + 3 \frac{4 x ^{2} + 4 x + 4}{3} - \frac{ln ( 3 )}{2}))) + C

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