Identify the Sequence 125 , 25 , 5 , 1

This is a geometric sequence since there is a common ratio between each term. In this case, multiplying the previous term in the sequence by ${\displaystyle \frac{1}{5}}$ gives the next term. In other words, ${\displaystyle a_n=a_1\cdot r^{n-1}}$.

Geometric Sequence: ${\displaystyle r=\frac{1}{5}}$

This is the form of a geometric sequence.

Substitute in the values of ${\displaystyle a_1=125}$ and ${\displaystyle r=\frac{1}{5}}$.