The first term is

a_{1}

The second term is obtained by multiplying the first by *r*

a_{1}r

The third term is obtained by multiplying the second by *r*

a_{1}r^{2}

The fourth term is obtained by multiplying the third by *r*

a_{1}r^{3}

We continue this pattern and can see that in general, the *n*-th
term is

a_{1}r^{n−1}