If we put x=1x we get,
However on expanding just the numerator we get that it is also equal to-
Therefore,
a0 = a2n
a1 = a2n-1
Or in general,
ar = a2n-r.......(i)
Given:
Put x= -x,
Put x = x2,
Coefficient of x2n in (iv) is = an
Multiplying (ii) and (iii),
Coeeficient of x2n in the RHS is,
We find from (iv) that this is equal to an
Again using the fact that ar=an-r we may find,
Manish Shankar good work :)
Upvote·0· Reply ·Mar 22 '13 at 3:50