Mister Exam

Lang:

Other calculators

How to use it?
Integral of d{x}:
Integral of lny
Integral of tg(2x)dx
Integral of x(2x²-5)dx
Integral of sqrt(cosx)*sinx
Identical expressions
X^ three *cos3x
X cubed multiply by co sinus of e of 3x
X to the power of three multiply by co sinus of e of 3x
X3*cos3x
X³*cos3x
X to the power of 3*cos3x
X^3cos3x
X3cos3x
X^3*cos3xdx

Solving integrals/ X^3*cos3x

Integral of X^3*cos3x dx

The solution

You have entered [src]

  1               
  /               
 |                
 |   3            
 |  x *cos(3*x) dx
 |                
/                 
0

\int\limits_{0}^{1} x^{3} \cos{\left(3 x \right)}\, dx

Integral(x^3*cos(3*x), (x, 0, 1))

Detail solution

Use integration by parts:

$\int \operatorname{u} \operatorname{dv} = \operatorname{u}\operatorname{v} - \int \operatorname{v} \operatorname{du}$

Let $u{\left(x \right)} = x^{3}$ and let $\operatorname{dv}{\left(x \right)} = \cos{\left(3 x \right)}$ .

Then $\operatorname{du}{\left(x \right)} = 3 x^{2}$ .

To find $v{\left(x \right)}$ :
1. Let $u = 3 x$ .
  
  Then let $du = 3 dx$ and substitute $\frac{du}{3}$ :
  
  $\int \frac{\cos{\left(u \right)}}{3}\, du$
  1. The integral of a constant times a function is the constant times the integral of the function:
    
    $\int \cos{\left(u \right)}\, du = \frac{\int \cos{\left(u \right)}\, du}{3}$
    1. The integral of cosine is sine:
      
      $\int \cos{\left(u \right)}\, du = \sin{\left(u \right)}$
    So, the result is: $\frac{\sin{\left(u \right)}}{3}$
  Now substitute $u$ back in:
  
  $\frac{\sin{\left(3 x \right)}}{3}$
Now evaluate the sub-integral.
Use integration by parts:

$\int \operatorname{u} \operatorname{dv} = \operatorname{u}\operatorname{v} - \int \operatorname{v} \operatorname{du}$

Let $u{\left(x \right)} = x^{2}$ and let $\operatorname{dv}{\left(x \right)} = \sin{\left(3 x \right)}$ .

Then $\operatorname{du}{\left(x \right)} = 2 x$ .

To find $v{\left(x \right)}$ :
1. Let $u = 3 x$ .
  
  Then let $du = 3 dx$ and substitute $\frac{du}{3}$ :
  
  $\int \frac{\sin{\left(u \right)}}{3}\, du$
  1. The integral of a constant times a function is the constant times the integral of the function:
    
    $\int \sin{\left(u \right)}\, du = \frac{\int \sin{\left(u \right)}\, du}{3}$
    1. The integral of sine is negative cosine:
      
      $\int \sin{\left(u \right)}\, du = - \cos{\left(u \right)}$
    So, the result is: $- \frac{\cos{\left(u \right)}}{3}$
  Now substitute $u$ back in:
  
  $- \frac{\cos{\left(3 x \right)}}{3}$
Now evaluate the sub-integral.
Use integration by parts:

$\int \operatorname{u} \operatorname{dv} = \operatorname{u}\operatorname{v} - \int \operatorname{v} \operatorname{du}$

Let $u{\left(x \right)} = - \frac{2 x}{3}$ and let $\operatorname{dv}{\left(x \right)} = \cos{\left(3 x \right)}$ .

Then $\operatorname{du}{\left(x \right)} = - \frac{2}{3}$ .

To find $v{\left(x \right)}$ :
1. Let $u = 3 x$ .
  
  Then let $du = 3 dx$ and substitute $\frac{du}{3}$ :
  
  $\int \frac{\cos{\left(u \right)}}{3}\, du$
  1. The integral of a constant times a function is the constant times the integral of the function:
    
    $\int \cos{\left(u \right)}\, du = \frac{\int \cos{\left(u \right)}\, du}{3}$
    1. The integral of cosine is sine:
      
      $\int \cos{\left(u \right)}\, du = \sin{\left(u \right)}$
    So, the result is: $\frac{\sin{\left(u \right)}}{3}$
  Now substitute $u$ back in:
  
  $\frac{\sin{\left(3 x \right)}}{3}$
Now evaluate the sub-integral.
The integral of a constant times a function is the constant times the integral of the function:

$\int \left(- \frac{2 \sin{\left(3 x \right)}}{9}\right)\, dx = - \frac{2 \int \sin{\left(3 x \right)}\, dx}{9}$
1. Let $u = 3 x$ .
  
  Then let $du = 3 dx$ and substitute $\frac{du}{3}$ :
  
  $\int \frac{\sin{\left(u \right)}}{3}\, du$
  1. The integral of a constant times a function is the constant times the integral of the function:
    
    $\int \sin{\left(u \right)}\, du = \frac{\int \sin{\left(u \right)}\, du}{3}$
    1. The integral of sine is negative cosine:
      
      $\int \sin{\left(u \right)}\, du = - \cos{\left(u \right)}$
    So, the result is: $- \frac{\cos{\left(u \right)}}{3}$
  Now substitute $u$ back in:
  
  $- \frac{\cos{\left(3 x \right)}}{3}$
So, the result is: $\frac{2 \cos{\left(3 x \right)}}{27}$
Add the constant of integration:

$\frac{x^{3} \sin{\left(3 x \right)}}{3} + \frac{x^{2} \cos{\left(3 x \right)}}{3} - \frac{2 x \sin{\left(3 x \right)}}{9} - \frac{2 \cos{\left(3 x \right)}}{27}+ \mathrm{constant}$

The answer is:

\frac{x^{3} \sin{\left(3 x \right)}}{3} + \frac{x^{2} \cos{\left(3 x \right)}}{3} - \frac{2 x \sin{\left(3 x \right)}}{9} - \frac{2 \cos{\left(3 x \right)}}{27}+ \mathrm{constant}

The answer (Indefinite) [src]

  /                                                                          
 |                                                   2             3         
 |  3                   2*cos(3*x)   2*x*sin(3*x)   x *cos(3*x)   x *sin(3*x)
 | x *cos(3*x) dx = C - ---------- - ------------ + ----------- + -----------
 |                          27            9              3             3     
/

\int x^{3} \cos{\left(3 x \right)}\, dx = C + \frac{x^{3} \sin{\left(3 x \right)}}{3} + \frac{x^{2} \cos{\left(3 x \right)}}{3} - \frac{2 x \sin{\left(3 x \right)}}{9} - \frac{2 \cos{\left(3 x \right)}}{27}

Simplify

The graph

Plot the graph f(x)

The answer [src]

2    sin(3)   7*cos(3)
-- + ------ + --------
27     9         27

\frac{7 \cos{\left(3 \right)}}{27} + \frac{\sin{\left(3 \right)}}{9} + \frac{2}{27}

2    sin(3)   7*cos(3)
-- + ------ + --------
27     9         27

\frac{7 \cos{\left(3 \right)}}{27} + \frac{\sin{\left(3 \right)}}{9} + \frac{2}{27}

2/27 + sin(3)/9 + 7*cos(3)/27

Numerical answer [src]

-0.166910646371241

-0.166910646371241

The graph

Use the examples entering the upper and lower limits of integration.

Other calculators

How to use it?

Identical expressions

Integral of X^3*cos3x dx

Limits of integration:

The graph:

Piecewise:

The solution