Algebra - binomial

62

The rth term is given by \frac{r(r+1)}{2}x^r-1

Now you want to find the sum

You can think of this as the derivative of something?

And then take the sum (Infact the double derivative?)

Give it a shot once...

1

Err , I think that -

Now , from the fundamentals of infinite G . P . - s ,

Differentiate each side of this identity twice to get -

262

Aditya Bhutra ·2011-06-18 11:18:10

from, binomial expansion for any index, we have
(1+x)^-3 = 1-3x + 6x² - 10x³ ......
now replacing x with -x,

(1-x)^-3 = 1+3x + 6x² + 10x³ ......

1

thanks for all your help..
i got another method too..using agp

binomial