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

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

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integral of cos^3(2x)

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

\frac{1}{2} (sin (2 x) - \frac{sin ^{3} ( 2 x )}{3}) + C

Solution steps

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

Apply u-substitution

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

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

Take the constant out:

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

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

Rewrite using trig identities

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

Apply u-substitution

: \int 1 - v^{2} d v

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

Apply the Sum Rule:

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

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

\int 1 d v = v

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

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

Substitute back

= \frac{1}{2} (sin (2 x) - \frac{sin ^{3} ( 2 x )}{3})

Add a constant to the solution

= \frac{1}{2} (sin (2 x) - \frac{sin ^{3} ( 2 x )}{3}) + C

\int \frac{x - 5}{x ^{3} - 3 x ^{2} + 7 x - 5} d x

\frac{d}{d x} (arcsin (9 x) + arccos (9 x))

\int \frac{x ^{3}}{a} - \frac{a}{x ^{3}} d x

\frac{d}{d x} (x^{22})

2 x y + (2 y + x^{2}) \cdot (\frac{d y}{d x}) = 0

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