scguy

From example 2: I can kind of understand the method used but i just don't know why that once the product rule has been used there is no way to just integrate the 2 terms. I know that it is the same term that we started with and that it has just been left in its integrand notation to keep things simple, i think that is correct. I have written on the RHS what i think the method is i would just like to know if i am on the right track, which if i am not is not really surprising to me

Hmm that is very interseting dak, now i have a question for u. How the heck would one go about solving this code or just finding the quadratic purely by mathematical means, is it even possible? Could there be some kind of procedure or logical way to do this or are the numbers in to many permutations thus requiring the use of a computer?

Hmm, i think a fundamental problem with mathematics or should i say the teaching of it is that we are taught how to use systems and procedure to find what we are looking for. If we could actually visualise or understand fully what we are doing then it could be much more fulfilling and easier too. When i am learning things from text books etc it is often the case that instead of explaining the theory and concept properly and extensively it will just rush into the methods without much consideration for the former. I often stop to just go through the concepts in my head when i am working on a new subject because it gives me insight into how i can apply it better etc. Granted there are gifted individuals that can instantly understand on a very deep level but for others it has to be taught.

U really know your stuff johnny5, the last example was very informative.

Thanks for the responses, i understand better now.

I have been taught to do it this way: Say i wish to integrate. (2x+1)^1/2 dx 1) u=2x+1 2) therefore... u^1/2 dx 3) du/dx= 2 4) u^1/2 du/2 (because du/dx=2) 5) therefore...1/2 u^1/2 du. At step 5 the integration is then performed, i have no problems with that. It says in the book that du/dx=2 should not be split up to make du/2=dx, but this is what is done anyway in all the examples Note, the only reason this is done in the first place is because u are not supposed to have more than 1 variable in the integrand. I cant make sense of it.

If anybody is still interested i got the system he used. It was a reverse numbering system of the alphabet ie Z=1 , Y=2 etc, it was then coded through the use of this quadratic: x^2+2x+7

Very impressive Dak:eek: , the teacher gave the answer and u were correct 100% i really am very surprised that it was broken by somebody. Maybe somebody could post another and i could write it down before it gets answered so i can do it myself

My maths teacher gave me this code that is based on an alphabetic numbering system, like A=1, B=2 etc. It is then encoded using a quadratic i dont know where to begin (70406535) (6825358770) (23136720258287) (175202) (70406535) (15026273520253570) (40673542535) (26236742535582) (735202582) (447175202535). (7040636787) (36787) (150106175175490). Each bracket represents a word.