What is the integral of cos^2(3x)sin(3x) ?

The integral of cos^2(3x)sin(3x) is -1/9 cos^3(3x)+C

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integral of cos^2(3x)sin(3x)

\int cos^{2} (3 x) sin (3 x) d x

- \frac{1}{9} cos^{3} (3 x) + C

Solution steps

\int cos^{2} (3 x) sin (3 x) d x

Apply u-substitution

= \int cos^{2} (u) sin (u) \frac{1}{3} d u

Take the constant out:

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

= \frac{1}{3} \cdot \int cos^{2} (u) sin (u) d u

Apply u-substitution

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

Take the constant out:

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

= \frac{1}{3} (- \int v^{2} d v)

Apply the Power Rule

= \frac{1}{3} (- \frac{v ^{3}}{3})

Substitute back

= \frac{1}{3} (- \frac{cos ^{3} ( 3 x )}{3})

Simplify

\frac{1}{3} (- \frac{cos ^{3} ( 3 x )}{3}) : - \frac{1}{9} cos^{3} (3 x)

= - \frac{1}{9} cos^{3} (3 x)

Add a constant to the solution

= - \frac{1}{9} cos^{3} (3 x) + C

What is the integral of cos^2(3x)sin(3x) ?
The integral of cos^2(3x)sin(3x) is -1/9 cos^3(3x)+C