Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °
You are not logged in.
Post a reply
Topic review (newest first)
- anonimnystefy
- 2013-01-26 13:30:01
You're welcome! 
- White_Owl
- 2013-01-26 04:31:27
Yes, it does look promising.
Thank you very much.
- anonimnystefy
- 2013-01-25 09:55:19
Hi White_Owl
You have multiplied by 3 instead of dividing by 3 when making the substitution...
- White_Owl
- 2013-01-25 09:21:44
Ok... Then:
And after substituting back u for x I have:
But now if I differentiate it back:
Where did 9 come from?
- anonimnystefy
- 2013-01-25 07:42:10
Hi White_Owl
Continuing on the first thing you tried:
Can you continue from here?
- White_Owl
- 2013-01-25 07:23:56
In my homework for this week I have a question:
If I do a substitution u=3x+25, then I have
Which does not help much.
If I try to find such u that du will eliminate x from numerator, then: du=1/x dx and u have to be ln(x)
Which is also not very helpful...
Finally I run the original integral through Maxima, and it gave me:
Which is very scary and I have no idea how it come to this formula.
So which "u" should I use? How to find such "u"? Or maybe there is another approach I should use? I am completely stuck.