11.5

[Pikabing]

For Q 34... I for alternating (-1) but I got that they rotate in pairs.. like in twos.. how do I show it? (also rotating cos and sin)  Does anyone understand what I am trying to say here? like.. how do you summarize this for R?

1. 2cos2x
2. -4sin2x
3. -8cos2x
4. 16sin2x

blah blah blah....

  Maybe it's late at night.. I am stuck on summarize this R crap for more than 30 mins now.. I am moving on... thanks in advance!


PS. Maybe I jsut did the derivative wrong?!?!?   I AM SO CONFUSED!!

[LiL-o]

for 36 .. I can't see the pattern ...
1  1  2  6   24    ... never been good with these series and sequence things...  

[Majin_Blues]

don't try to find a pattern... work with what you already know..

hint:  start with cosx and work your way up from there... (substitute an x with x² or whatever the heck is in the altered thingy... and so on)

do the same thing for the second question

(i'm answering the wrong question, aren't i?)

[Rogue_Knight]

For 34, I split it into two functions.
One for even n, the other odd n.
I'm not sure if this is legal.

For 36, my TA told me to refer it to 4(i), where we do as Blues said,  start with g(u)=cos(u), and find the P_g,n(u), and then evaluate at u=x^2.  Then if you multiply the P_g,n(x) by x, you get what we want, namely xcos(x^2).