Originally Posted by

**Khonics89** Consider the series for 1/1+x = 1+x^2+.....+x^n (1)

now use that to find the series for 1/1+x^2 (which is basically replace x with x^2

which produces

1/1+x^2 = 1+x^2+x^4+....+x^2n (2)

and now find a series with 2x/1+x^2

basically multiply (2) with 2x ....

no my question is how do i find the series for

ln(1+x^2) using those facts above me

i used equation (2)

1+x^2 = 1/(1+x^2+x^4+....+x^2n)

now i log both sides

ln(1+x^2) = ln(1/(1+x^2+x^4+....+x^2n)

which gives me

ln(1+x^2) = -ln(1+x^2+x^4+....+x^2n)

is this correct ??

or am i going no where with this proof ?

Tanks