Question

please tell this one..sum upto n terms...​

Answer 1

Answer:

Let

$s = 1 + 3x + 5 {x}^{2} + 7 {x}^{3} ..... \\ xs = \: \: \: \: \: \: \: x \: + 3 {x}^{2} + 5 {x}^{3} .... \\ - - - - - - - - - - - - - - \\ (1 - x)s = 1 + 2x + 2 {x}^{2} + .... \\ (1 - x)s = 1 + 2(x + {x}^{2} + ....) \\ \\ (1 - x)s = 1 + \frac{2x}{1 - x} \\ \\ s = \frac{1}{1 - x} + \frac{2x}{(1 - x) {}^{2} }$