English
Tamil Nadu Board of Secondary EducationHSC Science Class 11

Resolve the following rational expressions into partial fractions x+12(x+1)2(x-2) - Mathematics

Advertisements
Advertisements

Question

Resolve the following rational expressions into partial fractions

`(x + 12)/((x + 1)^2 (x - 2))`

Sum

Solution

`(x + 12)/((x + 1)^2 (x - 2)) = "A"/((x + 1)) + "B"/(x + 1)^2 + "C"/((x - 2))`

`(x + 12)/((x + 1)^2 (x - 2)) = ("A"(x + 1)(x + 2) + "B"(x - 2) + "C"(x + 1)^2)/((x + 1)^2 (x - 2)`

x + 12 = A(x + 1)(x – 2) + B(x – 2) + C(x + 1)2   ......(1)

Put x = 2 in equation (1)

2 + 12 = A(2 + 1)(2 – 2) + B(2 – 2) + C(2 + 1)2

14 = A(3)(0) + B × 0 + C(3)2

4 = 0 + 0 + 9C

⇒ C = `14/9`

Put x = – 1 in equation (1)

– 1 + 12 = A(– 1 + 1)(– 1 – 2) + B(– 1 – 2) + C(– 1 + 1)2

11 = A × 0 + B (– 3) + C × 0

11 = –3B

⇒ B = `- 11/3`

Put x = 0 in equation (1)

0 + 12 = A (0 + 1)(0 – 2) + B(0 – 2) + C(0 + 1)2

12 = – 2A – 2B + C

12 = `-2"A" - 2 xx - 11/3 + 14/9`

12 = `- 2"A" + 22/3 + 14/9`

2A = `22/3 + 14/9 - 12`

2A = `(66 + 14 - 108)/9`

= `(80 - 108)/9`

2A = `- 28/9`

⇒ A = `- 14/9`

∴ The required partial fraction is 

`(x + 12)/((x + 1)^2 (x - 2)) = (- 14/9)/(x + 1) + (-11/3)/(x + 1)^2 + (14/9)/(x - 2)`

`(x + 12)/((x + 1)^2 (x - 2)) =  - 14/(9(x + 1)) - 11/(3(x + 1)^2) + 14/(9(x - 2)`

shaalaa.com
Rational Functions
  Is there an error in this question or solution?
Chapter 2: Basic Algebra - Exercise 2.9 [Page 71]

APPEARS IN

Samacheer Kalvi Mathematics - Volume 1 and 2 [English] Class 11 TN Board
Chapter 2 Basic Algebra
Exercise 2.9 | Q 9 | Page 71
Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×