Find the integral 15ln (x^2-x+4)dx
in Calculus Answers by

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
To avoid this verification in future, please log in or register.

1 Answer

Start by completing the square: 
∫ 15 ln(x^2 - x + 4) dx 
= ∫ 15 ln((x - 1/2)^2 + 15/4) dx 
= ∫ 15 ln(w^2 + 15/4) dw, letting w = x - 1/2. 

Now, use integration by parts with 
u = 15 ln(w^2 + 15/4), dv = 1 dw 
du = 30w dw/(w^2 + 15/4), v = w: 

15w ln(w^2 + 15/4) - ∫ 30w^2 dw/(w^2 + 15/4) 
= 15w ln(w^2 + 15/4) - 30 ∫ ((w^2 + 15/4) - 15/4) dw/(w^2 + 15/4) 
= 15w ln(w^2 + 15/4) - 30 ∫ [1 - (15/4)/(w^2 + 15/4)] dw 
= 15w ln(w^2 + 15/4) - 30w + (225/2) ∫ dw/(w^2 + 15/4) 
= 15w ln(w^2 + 15/4) - 30w + (225/2) * (1/(√(15/4)) arctan(w / √(15/4)) + C 
= 15w ln(w^2 + 15/4) - 30w + 15√15 arctan(2w/√15) + C 
= 15(x - 1/2) ln((x - 1/2)^2 + 15/4) - 30(x - 1/2) + 15√15 arctan(2(x - 1/2)/√15) + C 
= (15/2)(2x - 1) ln(x^2 - x + 4) - 15(2x - 1) + 15√15 arctan((2x - 1)/√15) + C. 

I hope this helps!

by Level 10 User (57.4k points)

Related questions

1 answer
0 answers
1 answer
asked Dec 12, 2013 in Calculus Answers by anonymous | 3.5k views
1 answer
asked Jul 21, 2013 in Calculus Answers by asodisen Level 1 User (120 points) | 743 views
2 answers
asked Jun 19, 2013 in Calculus Answers by anonymous | 1.0k views
1 answer
asked Jun 18, 2013 in Calculus Answers by anonymous | 841 views
1 answer
asked May 14, 2013 in Calculus Answers by anonymous | 2.8k views
1 answer
1 answer
asked Apr 26, 2013 in Calculus Answers by anonymous | 826 views
1 answer
asked Jan 31, 2013 in Calculus Answers by anonymous | 674 views
1 answer
1 answer
asked Sep 16, 2012 in Calculus Answers by anonymous | 1.2k views
1 answer
asked Aug 27, 2012 in Calculus Answers by anonymous | 900 views
1 answer
asked Aug 22, 2012 in Calculus Answers by anonymous | 1.3k views
Welcome to MathHomeworkAnswers.org, where students, teachers and math enthusiasts can ask and answer any math question. Get help and answers to any math problem including algebra, trigonometry, geometry, calculus, trigonometry, fractions, solving expression, simplifying expressions and more. Get answers to math questions. Help is always 100% free!
87,516 questions
100,328 answers
2,420 comments
758,081 users