1 / | | 2 | 3*x *cos(3*x + 5) dx | / 0
Integral((3*x^2)*cos(3*x + 5), (x, 0, 1))
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.
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.
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 cosine is sine:
So, the result is:
Now substitute back in:
So, the result is:
Add the constant of integration:
The answer is:
/ | | 2 2*sin(5 + 3*x) 2 2*x*cos(5 + 3*x) | 3*x *cos(3*x + 5) dx = C - -------------- + x *sin(5 + 3*x) + ---------------- | 9 3 /
2*cos(8) 2*sin(5) 7*sin(8) -------- + -------- + -------- 3 9 9
=
2*cos(8) 2*sin(5) 7*sin(8) -------- + -------- + -------- 3 9 9
2*cos(8)/3 + 2*sin(5)/9 + 7*sin(8)/9
Use the examples entering the upper and lower limits of integration.