For the given integral problem: int (x^3+3x-4)/(x^3-4x^2+4x)dx , we may simplify by applying long division since the highest degree of x is the same from numerator and denominator side.
(x^3+3x-4)/(x^3-4x^2+4x) = 1+(4x^2-x-4)/(x^3-4x^2+4x) .
Apply partial fraction decomposition on the expression (4x^2-x-4)/(x^3-4x^2+4x) .
The pattern on setting up partial fractions will depend on the factors of the denominator. For the given problem, the factored form of the denominator will be:
(x^3-4x^2+4x) =(x)(x^2-4x+4)
=(x) (x-2)(x-2) or x(x-2)^2
For the linear factor (x) , we will have partial fraction: A/x
For the repeated linear factor (x-2)^2 , we will have partial fractions: B/(x-2) + C/(x-2)^2 .
The rational expression becomes:
(4x^2-x-4)/(x^3-4x^2+4x) =A/x +B/(x-2) + C/(x-2)^2
Multiply both side by the LCD =x(x-2)^2 :
((4x^2-x-4)/(x^3-4x^2+4x)) (x(x-2)^2)=(A/x +B/(x-2) + C/(x-2)^2)(x(x-2)^2)
4x^2-x-4=A*(x-2)^2+B*(x(x-2)) + C*x
We apply zero-factor property on x(x-2)^2 to solve for value we can assign on x.
x=0
x-2 = 0 then x=2 .
To solve for A , we plug-in x=0 :
4*0^2-0-4=A*(0-2)^2+B*(0(0-2)) + C*0
0-0-4 = A*(-2)^2 +0 +0
-4 =4A
-4/4 =(4A)/4
A =-1
To solve for C , we plug-in x=2 :
4*2^2-2-4=A*(2-2)^2+B*(2(2-2)) + C*2
16-2-4 = A*0 +B*0 +2C
10= 0 + 0 +2C
10 =2C
(10)/2= (2C)/2
C=5
To solve for B, plug-in x=1 ,A=-1 , and C=5 :
4*1^2-1-4=(-1)*(1-2)^2+B*(1(1-2)) + 5*1
4-1-4= (-1)*(-1)^2+B(1*(-1)) +5
-1= -1-B +5
-1= -B+4
-1-4= -B
-5=-B
(-5)/(-1) = (-B)/(-1)
B =5
Plug-in A = -1 , B =5, and C=5 , we get the partial decomposition:
(4x^2-x-4)/(x^3-4x^2+4x) =-1/x +5/(x-2) + 5/(x-2)^2
Then the integrand becomes:
(x^3+3x-4)/(x^3-4x^2+4x) = 1+(4x^2-x-4)/(x^3-4x^2+4x) .
=1-1/x +5/(x-2) + 5/(x-2)^2
Apply the basic integration property:int (u+-v) dx = int (u) dx +- int (v) dx .
int (x^3+3x-4)/(x^3-4x^2+4x) dx = int [1-1/x +5/(x-2) + 5/(x-2)^2] dx
=int1 dx - int 1/x dx +int 5/(x-2)dx + int 5/(x-2)^2dx
Apply basic integration property: int(a) dx = ax+C
int1 dx = 1x or x
Apply integration formula for logarithm: int 1/u du = ln|u|+C .
int 1/x dx=ln|x|
int 5/(x-2)dx= int 5/udu
= 5ln|u|
=5 ln|x-2|
Note: Let u =x-2 then du = dx .
Apply the Power Rule for integration: int (u^n) dx =u^(n+1)/ (n+1) +C .
int 5/(x-2)^2dx=int 5/u^2du
=int 5u^(-2)du
= 5 * u^(-2+1)/(-2+1)
= 5* u^-1/(-1)
= -5/u
= -5/(x-2)
Note: Let u =x-2 then du = dx
Combining the results, we get the indefinite integral as:
int (x^3+3x-4)/(x^3-4x^2+4x)dx =x-ln|x| +5 ln|x-2|-5/(x-2)+C
http://tutorial.math.lamar.edu/Classes/CalcII/PartialFractions.aspx
Friday, January 25, 2019
int (x^3+3x-4)/(x^3-4x^2+4x) dx Use partial fractions to find the indefinite integral
Subscribe to:
Post Comments (Atom)
Summarize the major research findings of "Toward an experimental ecology of human development."
Based on findings of prior research, the author, Bronfenbrenner proposes that methods for natural observation research have been applied in ...
-
Find the indefinite integral $\displaystyle \int \sec^4 \left( \frac{x}{2} \right) dx$. Illustrate by graphing both the integrand and its an...
-
x=4cost y=2sint First, take the derivative of x and y with respect to t. dx/dt=-4sint dy/dt=2cost Then, determine the first derivative dy/dx...
-
Ethno-nationalism is defined as "advocacy of or support for the political interests of a particular ethnic group, especially its nation...
-
Determine the area of the region bounded by the hyperbola $9x^2 - 4y^2 = 36$ and the line $ x= 3$ By using vertical strips, Si...
-
Both boys are very charismatic and use their charisma to persuade others to follow them. The key difference of course is that Ralph uses his...
-
Equation of a tangent line to the graph of function f at point (x_0,y_0) is given by y=y_0+f'(x_0)(x-x_0). The first step to finding eq...
-
Determine $\displaystyle \frac{dy}{dx}$ of $y^5 + x^2y^3 = 1 + x^4 y$ by Implicit Differentiation. $\displaystyle \frac{d}{dx}(y^5) + ...
No comments:
Post a Comment