Solve for the sum of the infinite geometric series 1+1/3+1/9+1/27+...

Answer 1

1+1/3 +1/9+ 1/27+... = S

multiply both sides by 1/3

S/3 = 1/3+1/9+ ...

S-S/3 = 1+1/3+1/9... -1/3-1/9-...

S-S/3 = 1

2S/3 = 1

S = 3/2 = 1.5 = 1 1/2 = sum of the infinite series