3*pi ---- 2 / | | 2 | -x *cos(x) dx | / pi
Integral((-x^2)*cos(x), (x, pi, 3*pi/2))
Use integration by parts:
Let and let .
Then .
To find :
The integral of cosine is sine:
Now evaluate the sub-integral.
Use integration by parts:
Let and let .
Then .
To find :
The integral of sine is negative cosine:
Now evaluate the sub-integral.
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:
Add the constant of integration:
The answer is:
/ | | 2 2 | -x *cos(x) dx = C + 2*sin(x) - x *sin(x) - 2*x*cos(x) | /
2
9*pi
-2 - 2*pi + -----
4
=
2
9*pi
-2 - 2*pi + -----
4
Use the examples entering the upper and lower limits of integration.