Question

jaldi answer dedo ji ​

Answer 1

Let S=1+2x+3x² +......∞ …(1)

multiply by x on both sides

xS=x+2x²+3x³ +.....∞ …(2)

Subtract (1) from (2)

S=1+2x+3x²+......∞

xS=x+2x² +3x³+.....∞

__________________

S(1−x)=1+x+x²+x³+.....∞

S(1-x) = 1/1-x

[sum of infinte G.P S∞ = 1/1-r]

S = 1/(1-x)²

So, Option D is the correct answer

Answer 2

Answer:

option d)is your answer