MHB Can Integration by Parts Solve This Tricky Question?

Click For Summary
The discussion centers on solving a challenging integration problem using integration by parts. The user proposes letting u = x^3 and dv = x^2√(x^3 + 1) for the integration by parts approach. An alternative method suggested involves using substitution with t = x^3 + 1. Participants are encouraged to provide assistance and insights on the effectiveness of these methods. The conversation highlights the complexity of the integration question and the various strategies that can be employed.
jaychay
Messages
58
Reaction score
0
Untitled 10.png
Can you help me with this question ?
I am really struck with this question.
Thank you in advance.
 
Physics news on Phys.org
Using integration by parts, I would let

$u = x^3$ and $dv=x^2\sqrt{x^3+1}$Alternatively, one could use the same setup for the method of substitution letting $t= x^3+1$
 
There are probably loads of proofs of this online, but I do not want to cheat. Here is my attempt: Convexity says that $$f(\lambda a + (1-\lambda)b) \leq \lambda f(a) + (1-\lambda) f(b)$$ $$f(b + \lambda(a-b)) \leq f(b) + \lambda (f(a) - f(b))$$ We know from the intermediate value theorem that there exists a ##c \in (b,a)## such that $$\frac{f(a) - f(b)}{a-b} = f'(c).$$ Hence $$f(b + \lambda(a-b)) \leq f(b) + \lambda (a - b) f'(c))$$ $$\frac{f(b + \lambda(a-b)) - f(b)}{\lambda(a-b)}...

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 16 ·
Replies
16
Views
4K