Find the values of x for which the series Inx + (Inx)^2 + (Inx)^3 + • • • converges and express the sum as a function of x.| infinite series problems and solutions | solved problems in calculus 

Solution

lnx+(lnx)^2+(lnx)^3+(lnx)^4+...

The geometric sum formula for infinite terms is given as:

If common ration |r| < 1, S_\infty=\frac{a}{1-r}

If |r| > 1, the series does not converge and it has no sum.

Where

a is the first term of series

r is the common ratio of series

n is the number of terms of series

This is a geometric series with ratio ln x . It converges for |ln x| < 1, -1 < ln x < 1,
1/e < x < e. The sum is \frac{(ln x)}{(1 - ln x)}