integral of 3cos^3(x)sqrt(sin(x))

Lösung

\int 3 cos^{3} (x) sin (x) d x

2 sin^{\frac{3}{2}} (x) - \frac{6}{7} sin^{\frac{7}{2}} (x) + C

Schritte zur Lösung

\int 3 cos^{3} (x) sin (x) d x

Entferne die Konstante:

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

= 3 \cdot \int cos^{3} (x) sin (x) d x

Umschreiben mit Hilfe von Trigonometrie-Identitäten

= 3 \cdot \int (1 - sin^{2} (x)) cos (x) sin (x) d x

Wende U-Substitution an

= 3 \cdot \int u (1 - u^{2}) d u

Multipliziere aus

u (1 - u^{2}) : u - u^{\frac{5}{2}}

= 3 \cdot \int u - u^{\frac{5}{2}} 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

= 3 (\int u d u - \int u^{\frac{5}{2}} d u)

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

\int u^{\frac{5}{2}} d u = \frac{2}{7} u^{\frac{7}{2}}

= 3 (\frac{2}{3} u^{\frac{3}{2}} - \frac{2}{7} u^{\frac{7}{2}})

Setze in

u = sin (x)

ein

= 3 (\frac{2}{3} sin^{\frac{3}{2}} (x) - \frac{2}{7} sin^{\frac{7}{2}} (x))

Vereinfache

3 (\frac{2}{3} sin^{\frac{3}{2}} (x) - \frac{2}{7} sin^{\frac{7}{2}} (x)) : 2 sin^{\frac{3}{2}} (x) - \frac{6}{7} sin^{\frac{7}{2}} (x)

= 2 sin^{\frac{3}{2}} (x) - \frac{6}{7} sin^{\frac{7}{2}} (x)

Füge eine Konstante zur Lösung hinzu

= 2 sin^{\frac{3}{2}} (x) - \frac{6}{7} sin^{\frac{7}{2}} (x) + C

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