A:
i know to to use each derivative to build a member out of it.
how to defne the n'th member??
regarding b:
i am sure that its correct because i took the series for e^x and multiplied eah member by x.
so the only error that could be is with the remainder .
i thought that if we multiply the remainder by x we add 1 to it
where is my mistake??
it doesnt matter
both sinx and sin3x transform into cosx and cos3x and vise versa
in both cases i get zero for every derivative
where did i stop early
i transformed power 3 function into a much easier to differentiate
power 1 function.
whats the problem??
what about A and B
are they ok??