find the sum of series 1+1/3+1/9+1/27+... to n terms sir this question answer 3/2(1-1/3n) sir please help me

Answer 1

r=1/3

Sum= A₁ (1-rⁿ /(1-r)

sum= 1(1-(1/3)ⁿ)/(1-1/3)
sum=(1-(1/3)ⁿ)/(2/3)= (3/2)(1-(1/3)ⁿ)