pi / | | 2 | x *sin(x*pi) dx | / 0
Use integration by parts:
Let and let .
Then .
To find :
Let .
Then let and substitute :
The integral of a constant times a function is the constant times the integral of the function:
The integral of sine is negative cosine:
So, the result is:
Now substitute back in:
Now evaluate the sub-integral.
Use integration by parts:
Let and let .
Then .
To find :
Let .
Then let and substitute :
The integral of a constant times a function is the constant times the integral of the function:
The integral of cosine is sine:
So, the result is:
Now substitute back in:
Now evaluate the sub-integral.
The integral of a constant times a function is the constant times the integral of the function:
Let .
Then let and substitute :
The integral of a constant times a function is the constant times the integral of the function:
The integral of sine is negative cosine:
So, the result is:
Now substitute back in:
So, the result is:
Now simplify:
Add the constant of integration:
The answer is:
/ | 2 | 2 2*cos(pi*x) x *cos(pi*x) 2*x*sin(pi*x) | x *sin(x*pi) dx = C + ----------- - ------------ + ------------- | 3 pi 2 / pi pi
/ 2\ / 2\ 2 / 2\ 2*sin\pi / 2*cos\pi / - --- - pi*cos\pi / + ---------- + ---------- 3 pi 3 pi pi
=
/ 2\ / 2\ 2 / 2\ 2*sin\pi / 2*cos\pi / - --- - pi*cos\pi / + ---------- + ---------- 3 pi 3 pi pi
Use the examples entering the upper and lower limits of integration.