Partial Fractions

SHOULD

\frac{x^{3}}{(x-1)^{3}(x-2)}

BE WRITTEN AS

\frac{A}{(x-1)^{3}}+\frac{B}{(x-1)^{2}}+\frac{C}{(x-1)}+\frac{D}{(x-2)}

IF NOT WHAT IS THE CORRECT WAY TO SPLIT IT?

39 Answers

1
greatvishal swami ·

waise karna kya hai

13
Двҥїяuρ now in medical c ·

[7][7]

how bhaiya???

62
Lokesh Verma ·

let me try and let me think more ;)

1
greatvishal swami ·

kyun bhaiya[7][7]

1
greatvishal swami ·

nahi ani i now think u r rite

wat i m saying is true whaen we hav a cubic or quadratic expression

i think[7][7]

11
Anirudh Narayanan ·

How did dimensional analysis creep into mathematics?

1
KR ·

ani is right but tat's a long way:::: i dunno whether such ques are asked in JEE

13
Двҥїяuρ now in medical c ·

plz anyone be the VOLUNTEER and do it!!

1
greatvishal swami ·

use bhool ja ani main sab kuch mila ke solve karta huin these r my fattas

62
Lokesh Verma ·

\frac{x^{3}}{(x-1)^{3}(x-2)} = \frac{A}{(x-1)^{3}}+\frac{B}{(x-1)^{2}}+\frac{C}{(x-1)}+\frac{D}{(x-2)}

multiply by (x-1)^3, and put x=1

A=1/-1 = -1

mulitply by x-2 and put x=2
8=D

now take x=0,
0=-1/-1 + B/1-c-4
thus, B-C=3

also x=3,

27/8=-1/8+B/4+C/2+8
-9=B/2+C

thus, -9=3b/2-3
-6=3b/2
b=-4

c=-7

see by putting x=4 if this satisfies!

62
Lokesh Verma ·

Aragorn, your method is right

in the first post..

62
Lokesh Verma ·

64/27x2 = -1/27-4/9-7/3+8/2
64/27x2 = -1/27-12/27-63/27+8/2
32/27 = -76/27+8/2
108/27=4

which is true..

hence this above holds..

can someone give a good justification?

62
Lokesh Verma ·

\frac{x^{2}}{(x-1)^{2}(x-2)} = \frac{A}{x-1}+\frac{B}{(x-1)^{2}}+\frac{C}{x-2}

can also be done.. there is no mistake at all..

62
Lokesh Verma ·

multiply by (x-1)^2

put x=1
B=-1

now multiply by x-2 and put x=2
4=C

put x=0
0=A/-1 + B/1 + c/-2
0=-A-1-2
A=-3

now substitute any value for x and verify :)

1
MATRIX ·

oh....bhaiyya.......[78][79][80][81][93].............

1
greatvishal swami ·

hain bhaiya wo maina galti se galti kar dee thi [4][4]

62
Lokesh Verma ·

You all are confused becasue it could have been written as

\frac{Ax^2+Bx+C}{(x-1)^3}+\frac{D}{(x-2)}

as well.

11
Anirudh Narayanan ·

exactly bhaiya.....

and i still don't understand why

\frac{x^{2}}{(x-2)^{2}(x-1)}

can't be written as

\frac{Ax+B}{(x-2)^2}+\frac{C}{x-1}

1
KR ·

it can be i think

33
Abhishek Priyam ·

A/(x-2)+B/(x-2)2+C/(x-1) ..(i)
=A(x-2)+B/(x-2)2+C/(x-1)

Ax-2A+B/(x-2)2+C/(x-1)

Let B'=B-2A
Ax+B'/(x-2)2+C/(x-1) ...(ii)

So U can write both i and ii.. botha are correct.. but (i) is preferred since its integration is easy.. :)

1
greatvishal swami ·

thnx advance main hi !!!

1
MATRIX ·

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11
Anirudh Narayanan ·

Arey, stop the war of smileys

Tell the easy way, Krishna Raj

106
Asish Mahapatra ·

u can if u want to ani.. or ..... but even im having a feeling that it will be wrong.. y not ask prophet sir?

1
greatvishal swami ·

ani bhool gaya kya dimentions se help le thodi

1
greatvishal swami ·

cube ke uper Ax3+Bx2+Cx+D likh

aur square term ke upar

Ax2+Bx+C likh

11
Anirudh Narayanan ·

Samajh me nahin aaya, yaar...

If u don't mind, can u pls represent it? (using latex)

1
greatvishal swami ·

k 1 min

11
Anirudh Narayanan ·

Thanx

1
greatvishal swami ·

\frac{Ax^{3}+Bx^{2}+Cx+D}{(x-1)^{3}}+\frac{Ex^{2}+Fx+G}{(x-1)^{2}}+\frac{H}{(x-1)}+\frac{I}{(x-2)}

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