Find the sum to indicated number of terms in each of the geometric progressions :
`x^3,x^5,x^7,.....n`terms `(ifx!=+-1)`.

Explanation

Here, a=`x^3` and r=`x^5/x^3`=`x^2`

We know that
`S_n`=`{a(1-r^n)}/{1-r}`

`s_n`=`x^3{(1-{x^2}^n)}/{1-x^2}`
`=x^3/{1-x^2}``[1-x^{2n}]`