117 views

If $l=1+a+a^2+ \dots$, $m=1+b+b^2+ \dots$, and $n=1+c+c^2+ \dots$, where $\mid a \mid <1, \: \mid b \mid < 1, \: \mid c \mid <1$ and $a,b,c$ are in arithmetic progression, then $l, m, n$ are in

1. arithmetic progression
2. geometric progression
3. harmonic progression
4. none of these

recategorized | 117 views

Let us take a = 0.1, b = 0.2, c = 0.3. Then l = 10/9, m = 10/8, n = 10/7 which are in harmonic progression.