Integral of (3x+4)/(x+1) dx
The solution
Detail solution
-
There are multiple ways to do this integral.
Method #1
-
Let u=3x.
Then let du=3dx and substitute du:
∫u+3u+4du
-
Let u=u+3.
Then let du=du and substitute du:
∫uu+1du
-
Rewrite the integrand:
uu+1=1+u1
-
Integrate term-by-term:
-
The integral of a constant is the constant times the variable of integration:
∫1du=u
-
The integral of u1 is log(u).
The result is: u+log(u)
Now substitute u back in:
u+log(u+3)+3
Now substitute u back in:
3x+log(3x+3)+3
Method #2
-
Rewrite the integrand:
x+13x+4=3+x+11
-
Integrate term-by-term:
-
The integral of a constant is the constant times the variable of integration:
∫3dx=3x
-
Let u=x+1.
Then let du=dx and substitute du:
∫u1du
-
The integral of u1 is log(u).
Now substitute u back in:
log(x+1)
The result is: 3x+log(x+1)
Method #3
-
Rewrite the integrand:
x+13x+4=x+13x+x+14
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫x+13xdx=3∫x+1xdx
-
Rewrite the integrand:
x+1x=1−x+11
-
Integrate term-by-term:
-
The integral of a constant is the constant times the variable of integration:
∫1dx=x
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−x+11)dx=−∫x+11dx
-
Let u=x+1.
Then let du=dx and substitute du:
∫u1du
-
The integral of u1 is log(u).
Now substitute u back in:
log(x+1)
So, the result is: −log(x+1)
The result is: x−log(x+1)
So, the result is: 3x−3log(x+1)
-
The integral of a constant times a function is the constant times the integral of the function:
∫x+14dx=4∫x+11dx
-
Let u=x+1.
Then let du=dx and substitute du:
∫u1du
-
The integral of u1 is log(u).
Now substitute u back in:
log(x+1)
So, the result is: 4log(x+1)
The result is: 3x−3log(x+1)+4log(x+1)
-
Add the constant of integration:
3x+log(3x+3)+3+constant
The answer is:
3x+log(3x+3)+3+constant
The answer (Indefinite)
[src]
/
|
| 3*x + 4
| ------- dx = 3 + C + 3*x + log(3 + 3*x)
| x + 1
|
/
∫x+13x+4dx=C+3x+log(3x+3)+3
The graph
log(2)+3
=
log(2)+3
Use the examples entering the upper and lower limits of integration.