Welcome :: Homework Help and Answers :: Mathskey.com

Recent Visits

  
Welcome to Mathskey.com Question & Answers Community. Ask any math/science homework question and receive answers from other members of the community.

13,435 questions

17,804 answers

1,438 comments

776,778 users

Integration help!!!!!!!!!!!!!!!!!!!!!!!!

0 votes

∫(x+10)dx/(2x^2+5x-3)

asked Jun 21, 2013 in CALCULUS by linda Scholar

1 Answer

0 votes

We can solve 2x^2 +5x -3

                     = 2x^2 + 6x - x - 3

                     = 2x(x + 3) -1(x + 3)

                     = (x + 3)(2x - 1)

Therefore ʃ (x+10)dx / (2x^2 +5x -3 ) = ʃ (x+10)dx / (x + 3)(2x - 1)

Let (x+10)/(x + 3)(2x - 1) = A/(x + 3) + B/(2x - 1)

 => (x+10)/(x + 3)(2x - 1) = (A(2x-1) + B(x+3)) / (x + 3)(2x - 1)

 =>  x + 10 = A(2x -1) + B(x + 3)

 If x = -3 then 7 = A(7) => A = -1

 If x = 0.5 then 10.5 = B(3.5) => B = 3

Therefore (x+10)/(x + 3)(2x - 1) = -1/(x + 3) + 3/(2x - 1)

Integrating on both sides we get,

                         ʃ (x+10)dx/(x + 3)(2x - 1) = ʃ-1dx/(x + 3) + ʃ3dx/(2x - 1)

                                                               = - ʃ dx/(x + 3) + 3 ʃ dx/(2x - 1)

                                                               = -log(x + 3) + (3)(log(2x - 1))(2) + c [Since ʃdx/x = logx + c]

                                                               =  6log(2x - 1) - log(x + 3) + c

Therefore    ʃ (x+10)dx/(x + 3)(2x - 1) =  6log(2x - 1) - log(x + 3) + c

                                                             

answered Jun 21, 2013 by joly Scholar

Related questions

asked May 15, 2015 in CALCULUS by anonymous
asked May 6, 2015 in CALCULUS by anonymous
asked Jul 26, 2014 in CALCULUS by anonymous
asked Jun 26, 2014 in CALCULUS by anonymous
asked Sep 20, 2018 in CALCULUS by anonymous
...